External monitor support

[Sanderr]

I’m going to give the quick answer and then do a follow-up post where I test this thoroughly.

Using my default setup which is:
MacBook -> USB-C Digital AV Multiport Adapter -> DisplayLink dock via USB

Everything is dead simple. Close MacBook to sleep. Then just turn on dock, plug single cable into MacBook, tap a key and you are up in a few seconds (monitors take a few seconds to wake from low power). Just unplug and open screen to go back to mobile. Switch off dock. I can repeat this procedure over and over with no flakiness.

When docked at my desk I can put the system to sleep from the Apple menu and my displays go to sleep. If I later hit any key it takes approximately 5 seconds for my displays to wake (go from red light to green). This is normal for my two 1440p displays no matter what I have connected to them.

So I find this a very production-ready solution.

BUT, I have begun testing using the dock only (no Multiport adapter). I’m doing this because I know some of you may run this way to save some money, although I don’t recommend it for performance reasons. It is a bit flaky this way. Examples: The internal screen is still shown in “arrange” even when in clamshell. Unplugging the laptop can result in some “phantom displays”. I have a feeling all of this can be worked around; but wanted to report.

I’ll go into all this in more detail when I have had time to do a full assessment. For now I recommend spending the extra on the Multiport adapter + Displaylink dock to keep things smooth and easy.

I'm looking into this setup as well. However, I don't really need extra ports so I was wondering; After the Multiport adapter, would any DisplayLink device work? There are quite a few adapters on the market that do just USB-a to DP/HDMI etc.

Also, does this need to be the Apple Multiport adapter, or would any usb-c dock work when connecting a DisplayLink adapter after it?

 

[MK500]

I'm looking into this setup as well. However, I don't really need extra ports so I was wondering; After the Multiport adapter, would any DisplayLink device work? There are quite a few adapters on the market that do just USB-a to DP/HDMI etc.

I believe so. Remember that it must be “DisplayLink”, as that is the magic that lets us have additional displays beyond Apple’s limitations. It’s likely the same DisplayLink chip in all the DisplayLink docks/adapters. I believe they just sell their chip to all these device manufacturers and they build their dongles/docks around it. Drivers are always downloaded directly from DisplayLink. Of course it’s always good to use something that you know has been tested by someone else already. Please let us know if you find cheaper/better options. I didn’t find any that were less than $140, but I didn’t look that long. I also like the features of this dock. It supports 4K dual or 5k single. It has BOTH DisplayPort and HDMI for each port, which is really convenient for me. And it has a power switch so isn’t wasting energy running when I don’t need it to.

Also, does this need to be the Apple Multiport adapter, or would any usb-c dock work when connecting a DisplayLink adapter after it?

I recommend only using the Apple adapter. My experience with other adapters that seem similar is that they can be flaky. I blame Apple for this, as I think some of this dongle crap isn’t as well documented/standardized as it should be.

 

[repoman27]

The OWC docks do not add DisplayPort inputs so no additional displays can be supported using their docks.


CORRECTION: M1 Macs have two DisplayPort connections to Thunderbolt, which can be used to provide full resolution (5K) on a tiled display like the LG UltraFine 5K, Dell UP2715K, or HP Z27q. But the two DisplayPort connections cannot be used to connect two separate displays. Whether a display is tiled or not, only one can be connected via Thunderbolt. This has been tested with a HP Z27q that can show the input resolution in its on screen menu. ioreg output confirms this for the LG UltraFine 5K. ioreg also confirms DSC for the 6K case.

I wonder if Apple made the second DisplayPort connection unusable for a second display so that they no longer have to write specs that say you can only connect half the number of 5K displays as 4K displays? Nuts.

There are quite a few places along the signal path where limitations can occur. It seems pretty clear that the M1's GPU only supports 2 display streams, thus it can't drive more than two displays.

The GPU architecture may also limit the maximum resolution. We know that 6016 x 3384 is possible, which would also make the equivalent scaled HiDPI setting (3008 x 1692) possible. Has anyone managed output at a higher resolution than that?

On the display engine side of things, one of the two streams is always routed to the DisplayPort 1.4a / eDP 1.4b interface connected to either the built-in panel or the protocol converter used for the HDMI 2.0b port on the Mac mini. The other stream is always routed to the integrated Thunderbolt/USB4 host router, which appears to have four separate DP IN adapters (two for each port). That would mean that the display engine of the M1 includes source outputs equivalent to 5 DisplayPort 1.4a 4-lane Main Links.

DisplayPort multi-link Single-Stream Transport appears to be supported over a single Thunderbolt link. I'm curious if a multi-link SST display can be driven using two USB Type-C to DP/mDP cables, one connected to each Thunderbolt/USB4 port of an M1 Mac, or if the two links must be from the lane adapters associated with a single port. Does this work on any Mac, with or without custom display overrides?

DisplayPort Multi-Stream Transport (MST) is probably not supported, because Apple.

HBR3 might be supported. I haven't seen any conclusive evidence one way or the other here. There are posts showing that 3840 X 2160 @ 120 Hz is possible, but not whether chroma subsampling was involved. I'd love it if someone would output a single-link DisplayPort stream that doesn't exceed the resolution limitations of the GPU yet definitely requires more than 17.28 Gbit/s so as to put this question to rest.

Display Stream Compression (1.2a?) appears to be supported. This also seems like it should be pretty straightforward to test for, although I suppose there aren't many displays that support DSC.

Y'CbCr 4:2:2 and 4:2:0 chroma subsampling appears to be supported.

HDCP 1.4 and 2.2 should be supported.

edit: Remove a word here, add a word there.

 

[Domino8282]

You don't need the monitor to charge your laptop, so TB3 is not needed.

Could you explain what you mean by this? Looking at the Dell description, it sounds like the 3419 will charge the laptop.

I love your software solution for managing an UltraWide display by the way!

 

[Sanderr]

There are quite a few places along the signal path where limitations can occur. It seems pretty clear that the M1's GPU only supports 2 display streams, thus it can't drive more than two displays.

The GPU architecture may also limit the maximum resolution. We know that 6016 x 3384 is possible, which would also make the equivalent scaled HiDPI setting (3008 x 1692) possible. Has anyone managed output at a higher resolution than that?

On the display engine side of things, one of the two streams is always routed to the DisplayPort 1.4a / eDP 1.4b interface connected to either the built-in panel or the protocol converter used for the HDMI 2.0b port on the Mac mini. The other stream is always routed to the integrated Thunderbolt/USB4 host router, which appears to have four separate DP IN adapters (two for each port). That would mean that the display engine of the M1 includes source outputs equivalent to 5 DisplayPort 1.4a 4-lane Main Links.

DisplayPort multi-link Single-Stream Transport appears to be supported over a single Thunderbolt link. I'm curious if a multi-link SST display can be driven using two USB Type-C to DP/mDP cables, one connected to each Thunderbolt/USB4 port of an M1 Mac, or if the two links must be from the lane adapters associated with a single port. Does this work on any Mac, with or with without custom display overrides?

DisplayPort Multi-Stream Transport (MST) is not supported, because Apple.

HBR3 might be supported. I haven't seen any conclusive evidence one way or the other here. There are posts showing that 3840 X 2160 @ 120 Hz is possible, but not whether chroma subsampling was involved. I'd love it if someone would output a single-link DisplayPort stream that doesn't exceed the resolution limitations of the GPU yet definitely requires more than 17.28 Gbit/s so as to put this question to rest.

Display Stream Compression (1.2a?) appears to be supported. This also seems like it should be pretty straightforward to test for, although I suppose there aren't many displays that support DSC.

Y'CbCr 4:2:2 and 4:2:0 chroma subsampling appears to be supported.

HDCP 1.4 and 2.2 should be supported.

I posted in another thread as well, but the HiDPI setting just above that, is not showing up for me. Might be because of what you said. This is what I posted:

Connected my 32" 4K LG monitor. Was blurry so I opened the settings: 3360 x 1890 was missing (this is what I used on my 15" MBP). After some searching in the display information, my Mac recognises it as 27" instead of 32". Maybe that's why the correct options are missing.

still doesn’t explain why it shows up as a 27” though. Tried resetting PRAM but that’s also not working.

 

[babatunde22]

Ok I've looked into my previous problem and it makes no sense. The display works perfectly connected to my 50 inch 4K flatscreen in my living room but is fuzzy when connected to my 24 inch monitor. Its scales properly with the 50 inch too so there's definitely something funky going on with Big Sur.

 

[sergioarista]

On diplaylink:

 

[Dragon M.]

Just FYI anybody hoping to go with the DisplayLink route. I wanted 3 monitors for my Mac Mini (since that what I ran previously).

I've found at least two features that are crippled by using DisplayLink:
1. Using your Apple Watch to unlock your computer or for passwords is a no-go. Apparently, this can't happen when someone is "observing your screen."
2. Netflix/Hulu/Disney+/AppleTV/any TV show and movie bought from iTunes will NOT play while a DisplayLink device is connected. A poor workaround is using Google Chrome to access the web-based ones, but won't work for the Apple controlled ones. Basically, using DisplayLink screws up anything that requires HDCP. I did some looking, and apparently, it doesn't matter if your dock/dongle supports HDCP, the macOS driver just can't handle it.

If anyone figures out any workarounds other than just using 2 screens, let me know.

 

[MK500]

Just FYI anybody hoping to go with the DisplayLink route. I wanted 3 monitors for my Mac Mini (since that what I ran previously).

I've found at least two features that are crippled by using DisplayLink:
1. Using your Apple Watch to unlock your computer or for passwords is a no-go. Apparently, this can't happen when someone is "observing your screen."
2. Netflix/Hulu/Disney+/AppleTV/any TV show and movie bought from iTunes will NOT play while a DisplayLink device is connected. A poor workaround is using Google Chrome to access the web-based ones, but won't work for the Apple controlled ones. Basically, using DisplayLink screws up anything that requires HDCP. I did some looking, and apparently, it doesn't matter if your dock/dongle supports HDCP, the macOS driver just can't handle it.

If anyone figures out any workarounds other than just using 2 screens, let me know.

I just tested this and can confirm it. On my setup with two 1440p displays I must temporarily unplug the right display when watching AppleTV on the left display. So the USB-C Digital AV Multiport Adapter fully supports HDCP content, but DisplayLink displays do not. And because of how DisplayLink works you can't even watch at all if the DisplayLink display is active (even if I move the window to non-DisplayLink screen).

 

[joevt]

I’m going to give the quick answer and then do a follow-up post where I test this thoroughly.

Using my default setup which is:
MacBook -> USB-C Digital AV Multiport Adapter -> DisplayLink dock via USB

Everything is dead simple. Close MacBook to sleep. Then just turn on dock, plug single cable into MacBook, tap a key and you are up in a few seconds (monitors take a few seconds to wake from low power). Just unplug and open screen to go back to mobile. Switch off dock. I can repeat this procedure over and over with no flakiness.

When docked at my desk I can put the system to sleep from the Apple menu and my displays go to sleep. If I later hit any key it takes approximately 5 seconds for my displays to wake (go from red light to green). This is normal for my two 1440p displays no matter what I have connected to them.

So I find this a very production-ready solution.

BUT, I have begun testing using the dock only (no Multiport adapter). I’m doing this because I know some of you may run this way to save some money, although I don’t recommend it for performance reasons. It is a bit flaky this way. Examples: The internal screen is still shown in “arrange” even when in clamshell. Unplugging the laptop can result in some “phantom displays”. I have a feeling all of this can be worked around; but wanted to report.

I’ll go into all this in more detail when I have had time to do a full assessment. For now I recommend spending the extra on the Multiport adapter + Displaylink dock to keep things smooth and easy.

For what purposes is the Multiport Adaptor used in this setup? The HDMI port? The Power Delivery port? The USB-A port? Or a combination of the three? The Multiport Adaptor contains a USB 3.0 hub (even though there's only one externally accessible port). Is the hub required to give separation between the DisplayLink device and the M1 port because of a problem with connecting directly to the M1 port using a non-hub based USB-C to USB-A adapter?

I'm looking into this setup as well. However, I don't really need extra ports so I was wondering; After the Multiport adapter, would any DisplayLink device work? There are quite a few adapters on the market that do just USB-a to DP/HDMI etc.

Also, does this need to be the Apple Multiport adapter, or would any usb-c dock work when connecting a DisplayLink adapter after it?

DisplayLink is just USB. It only needs a USB 3.0 connection. It could be from a hub or whatever. It usually is from a hub if the DisplayLink device has more than one port.

On the display engine side of things, one of the two streams is always routed to the DisplayPort 1.4a / eDP 1.4b interface connected to either the built-in panel or the protocol converter used for the HDMI 2.0b port on the Mac mini. The other stream is always routed to the integrated Thunderbolt/USB4 host router, which appears to have four separate DP IN adapters (two for each port). That would mean that the display engine of the M1 includes source outputs equivalent to 5 DisplayPort 1.4a 4-lane Main Links.

Four separate DP IN adapters just means the integrated Thunderbolt controllers have that many DP IN adapters. It doesn't necessarily mean the GPU can make 4 DisplayPort signals. In the ioreg there is a crossbar device (search for crossbar or xbar) which I think is used for switching two DisplayPort connections between the two controllers (each Thunderbolt port belongs to a separate Thunderbolt controller).

Pro Display XDR - Owners Thread

Just connected my MBA (16GB/8C) and everything seems to be good. Played a bit in the UI and watched some 4K videos in Safari (doesn't give me more I think?). No slowdowns I could see :) @joevt see attached files for the debug output. It seems that diagnose script didn't work and MacRumors...

forums.macrumors.com

The single Thunderbolt connected external display is called dispext0. The crossbar driver hints at four displays
"ufp-endpoints" = ("dispext0","dispext1","dispext2","dispext3")
and four Thunderbolt ports:
"dfp-endpoints" = ("atc0","atc1","atc2","atc3")
It seems we'll see 4 display/4 ports in a future Apple Silicon Mac.

But the crossbar device in the M1 Mac only has one external display and two ports:
"ufp-endpoints" = <"dispext0"> "dfp-endpoints" = <"atc0","atc1">

I suppose my Mac mini 2018 has a similar crossbar device (but it is not listed in ioreg - M1 Macs seem to expose a lot more stuff in the ioreg) - it has to be able to switch two DisplayPort signals between any two Thunderbolt controllers/four DP IN adapters also.

DisplayPort multi-link Single-Stream Transport appears to be supported over a single Thunderbolt link. I'm curious if a multi-link SST display can be driven using two USB Type-C to DP/mDP cables, one connected to each Thunderbolt/USB4 port of an M1 Mac, or if the two links must be from the lane adapters associated with a single port. Does this work on any Mac, with or without custom display overrides?

Any Mac can do dual link SST 5K from any two or one Thunderbolt 3 port (doesn't matter if they are different Thunderbolt controllers). I have a Dell UP2715K that I've tested with Intel Macs. With Thunderbolt 2, two ports is required because you can't put two HBR2 signals on a single Thunderbolt 2 cable.

We have yet to see 5K from an M1 Mac using two different Thunderbolt ports. 5K from a single Thunderbolt port has succeeded.

Page 4 | [Teardown] Late 2020 Mac mini: Apple Silicon M1, Th...

Page 4 | As soon as the M1 Mac mini arrived, I tore it down to confirm a few things Apple didn't make clear. All M1 Macs come with Thunderbolt 4 ports...

egpu.io

DisplayPort Multi-Stream Transport (MST) is probably not supported, because Apple.

We haven't seen anyone test MST. I suppose it won't work for multiple displays, as Apple doesn't allow that even for the two SST DisplayPort connections to the Thunderbolt port. A test of an old 4K MST display would be interesting.

iMac Pro Works With Apple's New Pro Display XDR, But Limited to 5K Resolution

There's an "Attach files" button that you can use to upload a file. For multiple or large files you can zip them up into a single zip file using the "Compress..." command in Finder (File menu or right click). You can compress multiple files/folders at once. There's some interesting stuff in...

forums.macrumors.com

Display Stream Compression (1.2a?) appears to be supported. This also seems like it should be pretty straightforward to test for, although I suppose there aren't many displays that support DSC.

I think ioreg (see link above) with a connected XDR display has shown DSC - at least it was a single connection and not split for 6K pixels.

Y'CbCr 4:2:2 and 4:2:0 chroma subsampling appears to be supported.

I think a log stream command can show a 422 or 420 connection - needs more testing/examples and a better predicate filter for the log stream command.

Mac mini driving two LG UltraFine (5K) Display thunderbolt displays?

Maybe it just detects FreeSync without supporting it? The images don't look like chroma sub sampling. It's really noticeable when it exists. The rtings.com web page has good example images. Do your displays have an option to show the color format? My Dell P2415Q shows YPbPr or RGB but doesn't...

forums.macrumors.com

HDCP 1.4 and 2.2 should be supported.

Not sure how to check for this. With M1 Macs, you can't use ioreg or AGDCDiagnose to get EDIDs or HDCP info.

 

[MK500]

For what purposes is the Multiport Adaptor used in this setup?

1) It delivers a HDMI port to drive the first 27” display at 1440p 60hz directly. This display gets full acceleration, HDCP for AppleTV+, etc. It is a native display output.
2) It powers the MacBook, which when combined with (1) allows the MacBook to wake up in Apple supported ”clamshell” mode (power is required for this).
3) It provides a 5gbit USB 3 port to the DisplayLink dock which gives us 1gbit Ethernet, USB for a keyboard and mouse, and a second 1440p display through a DisplayLink stream. A third monitor is optional.

 

[DenBeke]

I can confirm that two external displays work fine with a DisplayLink dock.

Using the Dell Universal Dock D6000 here for one display and a USB-C to HDMI dongle for the other and I can't see a difference between the two monitors.

 

[joevt]

1) It delivers a HDMI port to drive the first 27” display at 1440p 60hz directly. This display gets full acceleration, HDCP for AppleTV+, etc. It is a native display output.
2) It powers the MacBook, which when combined with (1) allows the MacBook to wake up in Apple supported ”clamshell” mode (power is required for this).
3) It provides a 5gbit USB 3 port to the DisplayLink dock which gives us 1gbit Ethernet, USB for a keyboard and mouse, and a second 1440p display through a DisplayLink stream. A third monitor is optional.

Since the Multiport Adapter provides USB 3.0, it means that it only has two lanes of DisplayPort to make a HDMI signal which is enough for 1440p 60Hz 10bpc HBR2 and 4K 60Hz 10bpc HBR3 4:2:2 or 4:2:0 but not possible to do 4:4:4 8bpc for HDMI 594 MHz timing. Even CVT-RB timing 533 MHz might be too much (too close to the 540 MHz limit for HBR3 4:4:4 8bpc?). I don't think the Multiport Adapter does DSC?

Correction: the adapter does support DSC which can be used to exceed the two lane HBR3 limit.

 

[hunkster]

I can confirm that two external displays work fine with a DisplayLink dock.

Using the Dell Universal Dock D6000 here for one display and a USB-C to HDMI dongle for the other and I can't see a difference between the two monitors.

Just to clarify. If you don't use the USB-C to HDMI dongle but just plug in the Dell D6000 into the macbook air(?), with 2 monitors connected to the D6000, they work properly right?

What refresh rate and resolution please?

Also, any issues with sleeping and waking, and clamshell mode?

Thanks.

 

[DenBeke]

Just to clarify. If you don't use the USB-C to HDMI dongle but just plug in the Dell D6000 into the macbook air(?), with 2 monitors connected to the D6000, they work properly right?

What refresh rate and resolution please?

Also, any issues with sleeping and waking, and clamshell mode?

Thanks.

I have two 1920x1200 displays at 60Hz.

Can't test with two displays in the D6000 since I haven't got the correct dongle here.

Currently I'm not quite happy with waking from sleep. I have to unplug and plug the D6000 so it recognizes my native-hdmi screen again. Don't know why it behaves that way. Only tried it once yet, so will report back once it's tested more.
Only have the Mac for a day now.

 

[UmichAg]

I have two 1920x1200 displays at 60Hz.

Can't test with two displays in the D6000 since I haven't got the correct dongle here.

Currently I'm not quite happy with waking from sleep. I have to unplug and plug the D6000 so it recognizes my native-hdmi screen again. Don't know why it behaves that way. Only tried it once yet, so will report back once it's tested more.
Only have the Mac for a day now.

Why would you need a dongle? Can’t you simply connect the dock to the Mac using the USBC cable and then have the two displays attached directly to the dock (with DisplayLink software enabled)?

 

[DenBeke]

Why would you need a dongle? Can’t you simply connect the dock to the Mac using the USBC cable and then have the two displays attached directly to the dock (with DisplayLink software enabled)?

Yes, that should entirely possible. But I just don't have the correct cables to use more than one of the ports on the DisplayLink dock.

Secondly, by using one native via a dongle, I have better performance on that main screen.

 

[jamesjingyi]

Just FYI anybody hoping to go with the DisplayLink route. I wanted 3 monitors for my Mac Mini (since that what I ran previously).

I've found at least two features that are crippled by using DisplayLink:
1. Using your Apple Watch to unlock your computer or for passwords is a no-go. Apparently, this can't happen when someone is "observing your screen."
2. Netflix/Hulu/Disney+/AppleTV/any TV show and movie bought from iTunes will NOT play while a DisplayLink device is connected. A poor workaround is using Google Chrome to access the web-based ones, but won't work for the Apple controlled ones. Basically, using DisplayLink screws up anything that requires HDCP. I did some looking, and apparently, it doesn't matter if your dock/dongle supports HDCP, the macOS driver just can't handle it.

If anyone figures out any workarounds other than just using 2 screens, let me know.

Can anyone else chime in on these limitations? Feel quite massive if so - especially if you can't watch content from Netflix/iTunes if any DisplayLink device is connected.

Apple Watch unlock is annoying but not a massive dealbreaker for me. If it stops content from playing I might have to cancel my M1 order ?

 

[jido]

Can anyone else chime in on these limitations? Feel quite massive if so - especially if you can't watch content from Netflix/iTunes if any DisplayLink device is connected.

Apple Watch unlock is annoying but not a massive dealbreaker for me. If it stops content from playing I might have to cancel my M1 order ?

I don't think Dragon M. would be lying. Is it a software issue though? I imagine DisplayLink would be HDCP-ready in general, but you need all the parts to play nice.

 

[MK500]

I imagine DisplayLink would be HDCP-ready in general, but you need all the parts to play nice.

I would not make this assumption. It's important to understand that "DisplayLink" is not a video transport industry standard like DisplayPort or HDMI. It is instead a very nifty workaround by the DisplayLink company. As far as I know the software is currently generating a frame-buffer in the background using Apple's screen capture code and then feeding that capture stream over USB; then decompressing it in a custom chip. It works, and it's super cool, but be aware that this sort of workaround is going to have inherent limitations.

This is why I recommend using an industry standard connection for a single external display, and only adding DisplayLink in addition if you need to add a second or third (or more) display.

 

[joevt]

I don't think Dragon M. would be lying. Is it a software issue though? I imagine DisplayLink would be HDCP-ready in general, but you need all the parts to play nice.

I think it's software. Apple needs to change their code to allow HDCP on certain displays while DisplayLink is doing its thing on its own displays. If the screen capture code is not capturing from the HDCP'd display then it should be given a pass. Maybe this granularity is not possible (a hardware limitation)?

 

[Dragon M.]

Can anyone else chime in on these limitations? Feel quite massive if so - especially if you can't watch content from Netflix/iTunes if any DisplayLink device is connected.

Apple Watch unlock is annoying but not a massive dealbreaker for me. If it stops content from playing I might have to cancel my M1 order 😞

Here's DisplayLink's official FAQ on the topic, very kindly telling you to pound sand.

Content protected video does not play on Mac while DisplayLink screens are connected – DisplayLink Support

support.displaylink.com

Here's their official response on the Watch, also telling you to blame Apple.

Unlocking with Apple Watch is not available while your screen is being shared - DisplayLink Forum

Unlocking with Apple Watch is not available while your screen is being shared Mac Software

www.displaylink.org

I'm also returning my Mac Mini now because on top of these problems, I'm getting even more problems. My monitor arrangement won't save after sleeping or restarting my Mac, so I have to rearrange them each time.

 

[OCDMacGeek]

Here's DisplayLink's official FAQ on the topic, very kindly telling you to pound sand.

Content protected video does not play on Mac while DisplayLink screens are connected – DisplayLink Support

support.displaylink.com

Here's their official response on the Watch, also telling you to blame Apple.

Unlocking with Apple Watch is not available while your screen is being shared - DisplayLink Forum

Unlocking with Apple Watch is not available while your screen is being shared Mac Software

www.displaylink.org

I'm also returning my Mac Mini now because on top of these problems, I'm getting even more problems. My monitor arrangement won't save after sleeping or restarting my Mac, so I have to rearrange them each time.

The arrangement resetting would be very annoying. Does this happen when you unplug from the DisplayLink dock and plug back in? (As I will often with my MacBook)

 

[Dragon M.]

The arrangement resetting would be very annoying. Does this happen when you unplug from the DisplayLink dock and plug back in? (As I will often with my MacBook)

It did happen with unplug and plugs. I sent in logs to DisplayLink Logs but I haven't heard anything back.

I've since returned my Mini and my DisplayLink, but the arrangement appeared to save for when I tested it with my 2019 Intel 15" MacBook Pro. So, it's possibly an issue limited to either just the M1 Macs (and can be fixed later by DisplayLink), or just limited to the M1 Mini (since it doesn't have an internal display).

 

[cmbarclay]

Well I just bought a LG 32UL950-W. Hope it works with my MPB M1.