Connection problems and routers


I am trying to connect using SmartFTP and keep getting these messages:

[12:55:39] SmartFTP v2.5.1006.48
[12:55:40] Resolving host name ""
[12:55:40] Connecting to Port: 21
[12:56:01] A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
[12:56:01] Cannot login waiting to retry (30s)...
[12:56:01] Client closed the connection.
[12:56:01] Active Help:

I have read all the knowledge base articles related to this problem. I have updated the firmware on my router (DSL-G604T) , I have checked that the IP address that I'm trying to connect to is correct, I have checked my ZoneAlarm settings are correct and my Windows XP firewall is switched off . I checked with my web provider yesterday that I have the correct u/n and pwd. Can anyone give me any ideas about what to do next?
This is a site that I have managed to use for several years using an ADSL modem - now that I use a wireless network & router I can't seem to figure out what to do to resolve this. I would be grateful for any ideas.