The fact that it says “Directory listing of / successful” means your FTP is working fine. The error afterwards is just the result of the server closing the connection due to inactivity, but this doesn’t affect your ability to use FTP.
I see nothing to suggest that our FTP server is not working as it should. But maybe there is a problem with the connection from the Site.pro builder. I can look into that.
EDIT: I tested it, and publishing from Site.pro seems to be working only intermittently. Sometimes it fails to connect, sometimes it fails to upload everything, and sometimes it just works. I’m not entirely sure what to make of this. But as far as I can tell: if publishing the site doesn’t work, just try again, it will usually work the second or third try.