I have a computer that will sometimes crash hard, frozen screen and mouse, awful static on the speakers and, interestingly, something coming over the ethernet port too. This interference goes up to the next device on the line, my network switch, and brings that to its knees too. Nothing can move through the switch while that computer is having a seizure. I can disconnect the wire at the switch and the network comes back to life within a minute.
I'm considering putting a sacrificial switch from my junk box inline to that one computer so maybe the rest of the network can survive its crashes.
That is probably the nic in said machine still being alive and unable to pass any received frames up to the os. When its buffer runs full, it starts spamming pause frames, which dumber switches just blast out every port effectively paralyzing the whole network segment.
You could verify this by running Wireshark on another machine, or try disable sending pause frames on the machine before it crashes via eg ethtool
In my case just a few weeks ago I had an AP that went bananas, and was directly connected via ethernet to a RPi4, and made the Raspbian kernel panic on the Broadcom driver, randomly. Not long after the AP stopped working completely.
I'm considering putting a sacrificial switch from my junk box inline to that one computer so maybe the rest of the network can survive its crashes.