Cannot connect to port 21

For some reason, port 21 isn't working. It worked fine a week ago or so, and no changes had been made, but then, in the middle of editing a site, smartFTP would not refresh a folder, and since then port 21 hasn't worked. Works fine on the guy sitting right next to me in the office, and we both have the same connection, it just won't work for me.

any thoughts?