Well thats where I was headed at first too... But then I find that I can take a non-networked pc and add it to the network and get on to the server. After about 10 minutes however, I get blocked on that computer as well. I unplugged both router and modem for 30 minutes earlier today and then plugged them back in and had no luck. I also opened up all the forwarding ports and still I cannot ping the server.

I found that if I hard wire a pc to the router though, it seems to bypass this issue... does that help at all?