Port 22 = SFTP?

I am setting up my backup policy but I noticed that I get errors when trying to do remote backups. It seems that I only get the errors when doing using port 22 and no errors when using port 21. When I use port 22, may I using SFTP protocol to do my remote backups?

Are you using a username that is allowed to ssh? Port 22 means ssh, so in order to allow sftp (aka ftp over ssh) that user needs to be allowed to ssh. There is an sftp module for proftp that can be used, but it is not 100% compatible with all sftp clients out there, I wouldn't recommend it.

Have you changed the SSH port?