hazza - 7:33 pm on May 8, 2010 (gmt 0)
Thanks for your interest.
Actually, I did try pinging the server from the command line (no problem) then ftp-ing the address from the command line. I was stumbling in the dark here, but I expected to be prompted for the username if everything was OK, but the window froze for a while then the server booted me off.
I should have made sure that the basics were sound, but although I tried different computers, different remote servers, different FTP clients, different ISPs, I started getting complicated and never thought about the router.