Not sure that I should open this here but.. I have this problem with online.net (French hosting provider) - the automated backups from Virtualmin to their FTP backup server failed, the connection is timing out. So, I have told them about this issue and they asked me to open the outgoing port range 0:65535 in the server's firewall.
Okay, it is working when I open outgoing 0:65535 ports but I do not wish to leave it this way with opened so wide range of ports on the server.
Is there any way that I can set specified port for FTP in the Virtualmin's backup feature (port 21 maybe, because I am able to connect to online.net's FTP server via SSH on port 21)?