USB Ethernet adapters randomly stop working on M1 MacBook Pro and macOS Big Sur

Hi,

I recently acquired the latest Apple Silicon MacBook Pro and came across a rather interesting issue.

During a network TimeMachine backup, my Ethernet link stopped working and I was able to reproduce the issue multiple times.

The problems happens with 2 different USB Ethernet devices, one being a USB-C hub, the other one is just a simple Ethernet to USB-A adapter.

Problem description and observations

The issue is always triggered when large amounts of data are being transferred over the Ethernet link, and affects any Application (it's easy to make the link crash by running a large file copy or a TimeMachine backup. I never managed to copy more than 30Gb at a time without the link going down).

In the crashed state, a ping to my gateway times-out, renewing the DHCP lease fails, the interface fallbacks to self-assigned address and setting a valid manual IP address doesn't bring the link back up.

ifconfig still reports the interface present, and the adapter is still present in System Information.

Interestingly, unplugging the CAT5 cable from the adapter still updates the link state in System Preferences (cable is/not connected) which could indicate that the computer still talks to the Ethernet chipset, but no network traffic gets through.

Informations and logging

Both adapters are running Realtek chipsets (RTL8153 and RTL8153B) which I believe is important to know, and appear as such in System Information:

USB 10/100/1000 LAN:

  Type:	USB
  BSD name:	en5
  Kext name:	com.apple.DriverKit.AppleUserECM.dext
  Location:	/System/Library/DriverExtensions/com.apple.DriverKit.AppleUserECM.dext
  Version:	1
  MAC Address:	xx:xx:xx:xx:xx:xx
  Product ID:	33107
  Vendor ID:	3034

With the Console open at the time of the crash, I couldn't identify anything network/driver related indicating a problem with the interface. It just fails silently as far as I was able to see.

Other users online have complained about similar issues, but the lack of detail makes it difficult to link their issues to mine for sure. Drivers and Big Sur are often discussed but I haven't been able to find specific evidence of their implication in the bug.

Next steps?

• What could I do to better track down the issue? Which logs to look at? Which tests to run?
• Anyone else experiencing the same crash?
• Apple aware of this issue?

Any help would be much appreciated.

Adrien.

Other comments to prevent obvious responses:

• • Yes, the energy settings of the Mac are set to disallow system sleep and allow network access (no interface sleep)
  • No weird/cheap adapters, converters or dongles are being used
  • The rest of the network is perfectly fine at the time of the crashes