Lessons learned:

use tmux, screen or at least nohup with an unstable internet connection, when doing filesystem repairs... FS survived, but anyways

Use a terminal multiplexer in general.
Also, on flaky internet connections, Eternal Terminal or mosh IN ADDITION to a terminal multiplexer.

Thanks for the suggestions. Unfortunately, I cannot install anything on the customer servers, beside some basic tools like tmux. Then it's only installed for the current session, so most of the time I use nohup (which is always available) to start critical processes. Pain in the ass.

@deman oof, that kinda sucks then.

It could have goes a whole different way.