In control panel, check in Security Centre. I don't use Norton so I'm not sure if it's suppoed to automatically disable the XP firewall. If you can't find any XP firewall info, make sure that your Norton's allowing LW.

If your router supports UPnP, enable it within the router & then choose the UPnP option on that same LW firewall page where you changed listening port.

Are you sure there's not another model number on the router? That one you gave me looks more like a serial number & there's no Google info at all.