Cannot add remote backup location

On my freedombox running on rockpro64 (installed debian, then freedombox), I used to have a remote backup location working.

I wanted to try changing the ssh port to something else than 22, so I removed the backup location, but I realized it was probably not possible, so I tried readding the backup location with port 22.

Then, I get the following error:

Error establishing connection to server: Command '['ssh', '-i', '/var/lib/plinth/.ssh/id_ed25519', '-o', 'UserKnownHostsFile=/var/lib/plinth/.ssh/known_hosts', '-o', 'BatchMode=yes', 'myuser@192.168.xx.xx', 'mkdir', '-p', './backup2/']' returned non-zero exit status 255. Read from remote host 192.168.xx.xx: Connection reset by peer client_loop: send disconnect: Broken pipe

The path is exactly the previous backup path, “myuser” is the previous backup user and on the remote location it owns its home directory and has write permission on it (in a previous attempt, it did not have write permission and the mkdir command was failing with a cause “cannot write”).

What could be the issue?

I haven’t used this feature yet, but is it possible that after removing the remote repository, the app generated a new SSH key pair? If so, you might need to update the key on the remote server.