If you have just installed Mosh server and tried to connect to it, you might have run into the following error:
$ mosh user@server /usr/bin/mosh: Did not find mosh server startup message.
This happens when your SSH session sends a locale that Mosh does not support. The fix is fairly easy, just configure your SSH not to send the LANG variable. To do that, open your
/etc/ssh/ssh_config and comment out the following line:
# SendEnv LANG LC_*
That’s it, now you can use your Mosh without any hiccups.