Ethernet broadcast storm on TBT3-UDZ with MacOS 12.2.1

this just began a few days ago, which happens to have been several days after my laptop updated to MacOS 12.2.1.

it’s happened three times now. i’m using a MacBook Pro 16" (2019 model), connected to the TBT3-UDZ via the included thunderbolt cable, and the dock is connected to my network switch. i can restore network connectivity by either powering off the MacBook, or by disconnecting its ethernet cable.


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

We haven’t encountered this behavior so far in our 12.2.1 testing, but there was a previously known issue with macOS prior to 11.3 that was causing broadcast storms. See here for more info:

When encountering the issue before we were only able to replicate it when the system was put into sleep mode. While turned on and actively running the issue wasn’t present previously. The issue was ultimately solved by a macOS update for Big Sur users with 11.3. macOS Catalina 10.15.x users needed an updated driver from Realtek (the Ethernet chipset manufacturer).

At this time there is no updated driver available for the Ethernet controller used in the dock to try for macOS Monterey 12.x, so if there is a new broadcast storm issue we will likely need to wait for Apple to correct their built-in Ethernet drivers as was done with Big Sur.

Can you describe when/how the broadcast storm appears to occur? Do you notice similar to above where it’s only happening if the system is sleeping, or will you lose a connection while actively using the system and dock?

Also, have you had the chance to try and SMC/NVRAM/PRAM reset on your Intel Mac just to see if there is any improvement? If not, it might be worth a try:

  1. Unplug the dock from the Mac and unplug power from the dock. Please leave the dock disconnected until the final step.
  2. Perform an SMC reset:
  3. Perform an NVRAM/PRAM reset:
  4. After logging back in, wait about 30-60 seconds, then plug power in to the dock and plug the dock in to the Mac and see if the behavior has improved.

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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