In December 2021 OSC updated its firewall to enhance security. As a result, SSH sessions are being closed more quickly than they used to be. It is very easy to modify your SSH options in the client you use to connect to OSC to keep your connection open.
In ~/.ssh/config (use the command
touch ~/.ssh/config to create it if there is no exisitng one), you can set 3 options:
TCPKeepAlive=no ServerAliveInterval=60 ServerAliveCountMax=5
Please refer to your SSH client documentation for how to set these options in your client.