Fixing the firewall situation may or may not fix your problem, but it's best if you do configure your system to allow LW full access. For your device, I'm not sure its UPnP abilities are that good. Previous feedback is that it doesn't work very well. Thus I'd recommend port forwarding if you're willing. Most important step is the very 1st step which is setting up a static ip. Port Forwarding for the Belkin F5D5230-4

Make sure your software firewall is configured for LW. I'm guessing you're running Windows XP SP2. So, (advisable not to have 2 active firewalls b/c they can interfere with each other); Firewall configuration instructions (click on link)

"If" you're running XP SP2, then get an SP2 patch: MS & 3rd party patches lvlord is probably the best.