On my work computer, I regularly SSH into two unrelated servers. Sometimes the SSH session locks up (does not respond to keyboard input). When locked up, I can SSH in via a second open terminal, that works but does not unfreeze the frozen terminal. Pressing
~. takes some time before the terminal disconnects and gives me a local CLI. I regularly SSH into both those servers from home with no problems, so I suspect that the issue is on my local work computer.
Does the problem occur with other terminals? Yes, the problem occurs with both Konqueror and with Terminator.
Does the problem occur to both remote servers at the same time? No
Does the problem occur with any particular application running on the server? Both with and without GNU Screen, both on the CLI and in VIM.
To test, I just opened four terminals: two Konqueror terminals, one to each server; and two Terminator terminals, one to each server. After about an hour, only one (Terminator) terminal locked up. The other terminal to the same server did not lock up, and neither terminal to the other server locked up. Of course, I tried Ctrl-Q in the locked up terminal to see if an errant Ctrl-S had been sent, but that did not resolve the issue. Screen was not running in the terminal that locked up (neither in the native session that is running the SSH, nor the SSH session itself).
UPDATE: An hour later the server locked up in Terminator has finally disconnected with "Write failed: Broken pipe" and I have a working local CLI, and the two servers in Konsole are also locked up.