I have a belkin 7230-4 and had the same problem.
I was using www.dynu.com
to foward to my WAN IP. What I got was my setup home page!!!!
After a few days I eventually phoned belkin tech support and they said the router uses port 80 to display the setup page.
My solution was to port forward from my www.dynu.com
account to port 8080 and then on my router I set up virtual server or port forwarding to send port 8080 to my LAN IP on port 80, therefore going around the port 80 setup on the router. It's working a treat!
It's a pity belkin are a little stupid thought because when you set up a preinstalled webserver config on port forward to actually sets port forward 80 to your LAN IP 80 which will never work because the setup page picks up the communcation.
Also with my router you can't open your WANIP (your modems IP with your ISP) and see your webpage, you have to goto a 3rd party computer to see it working. Try a mates or phone a friend.
Not sure if this helps, but you problem seemed very similar to mine.