I have the same issue.
ThinkPad P53s with Lenovo dock 40AS.
Network connection stops working at random moments during MS Teams meetings.
Disconnecting and re-connecting ethernet cable during meeting fixes the issue temporary.
Issue ONLY appears during MS Teams meetings, but is still present after meeting ends.
It is the entire network connection that stops working, affecting all applications on the PC.
I tried updating both dock drivers and dock firmware, but it did not fix the issue.
Issue does NOT appear when connected over WiFi or PCs own internal ethernet adapter.
Also issue does not appear when using a USB ethernet adapter.
My current workaraound:
Instead I use a StarTech USB to ethernet adaptor connected to the docking station.
This results in a reliable ethernet conenction through the dock:
[Laptop] <--USB--> [Dock] <--USB--> [StarTech] <--Ethernet