So the connection icon are arrows when they are there (occasionally there are neither). Also, although one computer has a fixed IP, the other will be a laptop, so a constantly changing IP. The only thing that might make sense is the router issue, although I have a gigabit switch downstream of the cable modem, I'll investigate that issue. Also, the PC is slow, so I'm thinking that might be an issue if BT takes a bit of overhead above FTP.