Network Connectivity After Accessing Other Computer

I lose all network capabilities on my 15" MacBook Pro 2018 (specs attached). This is REPEATABLE every.single.time.

I have a file on my laptop I want to copy to a different computer. I connect to that computer (not running Big Sur. Connecting in itself is pretty slow, but it does connect & I can see the shared folders on that computer). I will start the file copy (small file, less than 10 mb). The file copy sits and tries to complete. Eventually I will get a "Server Connection Interrupted" error message, and the copy fails. At this point ALL NETWORK CONNECTIVITY from my Big Sur MacBook Pro NO LONGER WORKS. Including Internet. It's as though the ethernet cable was unplugged. This happens on both wired and wireless connections.

I have also seen this happen when trying to scan on a network attached printer. The initial connection works (it sees the printer), but within 10 seconds or so it hangs. And after that, I have no network connectivity at all.

HIGHLY annoying. And completely repeatable. Really, really hope this is fixed via patch soon.