After three days, problem solved. Posting some additional info for anyone stumbling on this in the future.
Been here quite a few times. Not able to FTP, yet other users from other locations and support say "it's all good, it's on you."
First suspect is your local network, reboot and routers at your disposal as mentioned.
Try switching between passive and non passive mode, often changes in routers between you and the server can accept one and not the other.
You've already tried both clients, but you can also try command line FTP just to test it. (old school! :-) )
Start -> run type cmd, press enter, to DOS. Type FTP/press enter, you should get ftp>, which means you are in the command line ftp program. Type help/press enter for available commands. Just see if you can connect.
Last time it did this, oddly enough, I was also having problems with IE. In trying to fix IE, it revealed a link to "diagnose networking problems" in the "cannot connect to server" page. I hit the link, figuring it would wind up at something unhelpful, but it actually found a damaged TCP/IP file in my system, and fixed it. The FTP problem went away with it.
I'm not sure how to guide you through diagnosing TCP/IP problems from anywhere else, but it's something to track down.