M1 Macs only support one single external display via *ALL* Thunderbolt 3 ports.

[Anonymous Freak]

Just got my M1 Mac mini.

Can confirm - only one single display over Thunderbolt, regardless of how you attempt to connect.

I tried:

• Two USB-C-to-DisplayPort connections direct to back of Mini - only the first one got signal.

I tried a Thunderbolt 3 Dock that has two DisplayPort connections, one DP-enabled USB-C, plus a Thunderbolt 3 "outbound" connection - when connecting to my Intel MacBook Pro, to support two displays in macOS, I have to use one DisplayPort connection, and the outbound TB3 via USB-C-to-DisplayPort. (In Windows 10 on the same MBP, I can run two DisplayPort plus a third on the TB3 outbound. The "only one on DP, the other on TB3" is a macOS limitation.)

• One DisplayPort, one USB-C-to-TB3-port - this is what works on my MBP in macOS - if I plug the DP in first, then the TB3, the TB3 takes precedence, only displaying on the display on the TB3 port. If I plug the TB3 in first, the DisplayPort is ignored. (Both are true for any of the "DisplayPort" connections, the two native DP, or the DP-enabled-USB-C.)
• Two DisplayPort - same as two direct to the ports on the Mini, only the first one is recognized. (Again, doesn't matter which two DisplayPort, either the two full ones or the DP-equipped-USB-C.)

I tried two Thunderbolt 3 Docks - one display to each TB3 dock. Only the display on the first TB3 dock was recognized, regardless of port plugged in to on either one. Unlike connecting to a TB3 port on a single dock, plugging in to the TB3 on the second-connected dock doesn't make that display take over.

The *ONLY* way to get two displays is one to the HDMI port, and one to a TB3 port (either direct or through a dock.)

This is disappointing, because I was hoping to use dual displays through a TB3 dock. Oh well.

The tech specs for the MBA and MBP both specify only one single external display - I'm guessing that internally they route the "HDMI" signal to the internal display, so if you close the lid, you lose that signal. (It's almost certainly eDP - embedded DisplayPort, not HDMI, but that's the "display channel" used for HDMI on the Mini.)

(Yes, I originally posted this as a comment in another thread - I figured it was worth a top-level post, as people will be asking about it.)

 

[ruslan120]

That’s a shame. I was going to try that tomorrow.

I just wrapped up a tutorial on how to connect up to six screens - tldw: DisplayLink supports Big Sur and you can connect additional displays over USB (quality is almost native at least in my experience)

 

[MK500]

DisplayLink supports Big Sur and you can connect additional displays over USB (quality is almost native at least in my experience)

I’m definitely seeing very low framerate for 4K full screen video playback over Displaylink. Its great for most things, but definitely inferior to native.

 

[ruslan120]

I’m definitely seeing very low framerate for 4K full screen video playback over Displaylink. Its great for most things, but definitely inferior to native.

Agreed, quality is almost native in terms of general productivity, with the exception of strenuous tasks**