iMac Pro Ethernet port not working - any ideas?

[ascender]

I've just tried an ethernet cable for the first time on this machine as I have some large files to transfer and its not working. Its an iMac Pro running the latest version of Big Sur.

In the preferences pane, it just says the cable isn't connected.

So far I've tried...

• Different switchport
• Different cable
• Network port is showing up in system info
• No problems are found with the Apple diagnostics
• I've tried deleting and re-enabling the service

My next step was going to be to reinstall macOS, but wanted to ask on here first in case anybody has had similar issues. Not much has turned up in Google so far.

Thanks!

 

[Slartibart]

First things first: did you check wether the Ethernet cable works? 🤓 With a different machine connected to your switch or router?
Then: Which Mac Pro model are you using? Which version of MacOS?


EDIT: WLAN works?

Besides: boot your Mac in recovery mode -> When you enter into the "recovery mode", select the "Utility Disk" in the OS X Utility list.

Select the primary boot drive on the left side sidebar. Unless you haven’t renamed it, Macintosh HD is the boot drive. If you have changed the main boot drive then select that drive.

If you have FileVault, then in that case the main boot drive would be greyed out or not selectable. In that case, go to File -> Unlock and then center the FileVault password to open the main boot disk. You can skip this step if that is not the case.

Mount the main boot disk by going to File -> Mount in the menu bar.

While being in the recovery mode, launch the terminal app. Enter the code given below and tap the return key. Enter the password if necessary.

rm -rf "/Volumes/The-Name-of-Your-Hardisk/System/Library/Extensions/AppleKextExcludeList.kext"

Close the terminal app and restart the Mac.

 

[ascender]

Yes, I know the cables and switch ports are all good.

WLAN works fine.

Thanks, will try that sequence just now.

 

[ascender]

No joy with any of that and have also reinstalled Big Sur.

 

[Fishrrman]

SMC reset?
PRAM reset?

If nothing else you try works, perhaps the easiest workaround is to buy a 3rd-party USB/ethernet adapter and use that instead.

Be sure to confirm that it has Mac drivers or is known to work with the Mac before you buy...

 

[ascender]

Yes, have done both the usual resets and tried deleting all the network preferences files.

There's no crud in the network port and yes, it works with a usb-c 1 GBps LAN adapter.

I was thinking about downgrading to Mojave as a last ditch but that seems very very unlikely to work.

en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
options=567<RXCSUM,TXCSUM,VLAN_MTU,TSO4,TSO6,AV,CHANNEL_IO>
ether d0:81:7a:da:aa:33
nd6 options=201<PERFORMNUD,DAD>
media: 1000baseT <full-duplex> (none)
status: inactive

 

[ascender]

No joy here at all, but one of the guys in the office has also just bought a second hand iMac Pro and is having the exact same issue. Looks like both iMacs were manufactured in 2018.

He's been speaking to the people who sold the iMac and they've said they have seen this issue before with some Macs which have the 10Gbps NICs in them. They've apparently had issues whereby they can only get them working with certain network switches like Cisco and Juniper. On the more consumer-level and home network devices, they're unable to get them to recognise a cable on automatic or manual settings.

We've got a couple of Mac Minis with 10Gbps NICs in them and they've worked at both our locations, but I wonder if there's something in this?

I don't need Ethernet, its a nice to have for me, but I can see how my colleague needs it due to the work he does.

 

[BrianBaughn]

You should test it without the switch on the network to see.

 

[ascender]

You should test it without the switch on the network to see.

I've tried that with my current router and an old one - no joy.

 

[njvm]

Have you tried entering the IP address, subnet mask and dns server manually. The link below indicates that this fixed the problem for a Mac Mini with 10GB NIC?

2020 Mac Mini Ethernet port issue

I just bought a 2020 Mac Mini with 10 gigabit ethernet. I plugged in a cat6 cable into the mac mini's ethernet port and connected it to the wireless router, but it won't connect to the internet, sa...

apple.stackexchange.com

 

[wilberforce]

Do you have another Mac you can connect directly with an Ethernet cable (no router) to create an ad hoc network?

Use Ethernet to connect two Mac computers

On your Mac, use an Ethernet cable to connect two computers and share files or play network games.

support.apple.com

 

[ascender]

Have you tried entering the IP address, subnet mask and dns server manually. The link below indicates that this fixed the problem for a Mac Mini with 10GB NIC?

2020 Mac Mini Ethernet port issue

I just bought a 2020 Mac Mini with 10 gigabit ethernet. I plugged in a cat6 cable into the mac mini's ethernet port and connected it to the wireless router, but it won't connect to the internet, sa...

apple.stackexchange.com

Yip, that doesn't make any difference, whether on ipv4 or ipv6. Same as forcing the settings for the physical stuff.

All very weird.

Our Mac mini with 10 Gbps works without any changes being made.

 

[ascender]

Do you have another Mac you can connect directly with an Ethernet cable (no router) to create an ad hoc network?

Use Ethernet to connect two Mac computers

On your Mac, use an Ethernet cable to connect two computers and share files or play network games.

support.apple.com

Hmm, that's a good idea and I think the only thing I've not tried yet.

Looks like the other guys have given up and sent their machine back to be tested by the firm they bought it from who did say they used the Ethernet connection when building the machine so will be interesting to see what happens.

 

[Ledgem]

Can't help with the native port, but Apple did make Thunderbolt to ethernet adapters. There's a glut of them on eBay for relatively cheap... if you or your colleague need ethernet and aren't using all of your Thunderbolt ports, that's a route that can be taken to at least be able to use ethernet. Shouldn't have to with a dedicated port already on the computer, but at least it's an option. Alternately, many Thunderbolt hubs also have ethernet ports built in - so if you want to use the Thunderbolt port for more than converting it into a simple ethernet port, there's that.

 

[BrianBaughn]

Since your 10Gbps Mini works on the network (same macOS?) and your 10Gbps iMac shows that the ethernet device is working I'm inclined to think it's the port.

Have you tried connecting the Mini directly to the iMac via ethernet?