TBT3-UDZ, Macbook Pro & Big Sur 11.1 - Ethernet Drop Outs, Displays not Aways Recognized

Macbook Pro 16" running Big Sur 11.1 - Two problems are recurring

  1. At random intervals, the Ethernet connection will drop. It will report a self assigned IP and attempting to renew the DHCP lease doesn’t work. The only way to restore the connection to normal operation is unplug/plug the thunderbolt 3 connection. This is new behavior since 11.1

  2. Unplugging/Plugging from dock results in connected displays (HDMI in both cases) from being recognized normally. Unplug/plug the HDMI from the dock and things come back to life most of the time. Occasionally, restarting the macbook is required. This behavior happens regardless of the dock port, cable or display connected. I’ve also tried using Displayport to HDMI adapters and the behavior is the same. This behavior has been consistent since before 11.1.

Any suggestions?

Hi Joel,

Thank you for contacting Plugable support! Sorry to hear about this issue. I’d be more than happy to assist you.

For the display issues, we’ve been seeing increased display problems with or without docks in use after the update to Big Sur 11.1. There’s actually a huge thread on the Apple forums with 19 pages of replies about various troubles: https://discussions.apple.com/thread/252174979

We’ve been told these issues are being looked into, for the moment we don’t have a solution. We’re hopeful the next macOS update may help this kind of behavior.

I’d be curious to hear what brand and model monitors you’ve got so I can see if we’ve seen those models have troubles for other customers.

For the network failures, there is a known issue with the Apple provided built in macOS Ethernet drivers for the Realtek RTL8153 USB 3.0 Ethernet chipset used in our dock (and many other docks and USB Ethernet adapters on the market). When put to sleep, the problematic driver creates an Ethernet broadcast storm which can overwhelm some Ethernet routers.

For macOS Big Sur 11.x users, at this time there is no updated driver available due to Apple’s change in driver models from “KEXT” to “DEXT”. Realtek is currently developing new drivers to support this new macOS version. For now, we recommend to disable your Mac from sleeping to prevent this issue, or use WiFi instead of Ethernet until the new driver is available.

(For macOS Catalina 10.15.x users we can provide you with an updated driver and installation instructions.)

Please don’t hesitate to let us know of other questions.

Thanks again for contacting Plugable support and best wishes!

Joshua Henry
Senior Engineer | Product Owner
Plugable Technologies

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