GitLab fails to push to mirrors using SSH

GitLab is failing to push via SSH:

2:Fetching remote remote_mirror_a078d732c4245135f6d303fe93d317db failed:
connect to host github.com port 22: Connection refused
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

But using https:// the push to the same repo was successful.