When you set up port forwarding, did you make sure to set up a static IP address first? If you didn't do the port forwarding, ask whoever did it Have a look through these instructions, there's a link in there to static IP setup: Port Forwarding for the Airlink 101 AR525W

Make sure that LW's listening port, port in the 'manual port forward' box & port forwarded within the router's config are all the same number.

If your router supports UPnP (check the router manual), you could try enabling that within the router's config & then choosing the UPnP option within LW's tools > options > advanced > firewall.

I guess you tried all the fixes in that 'if LW will not conect' thread? After you deleted the preferences folder, did you have to go through LW's setup wizard all over again?