Port 80 is often blocked in the router because it's such a common port to hack through. Try changing it to something else. I use something in the 8200 range but usually don't access DVRs directly from outside, using the DDNS instead. Haven't had a problem accessing a DVR, but most of them aren't 2Wire or ATT, either. When I was using my music server, I had opened the ports in my 2Wire 2701 gateway and never had issues with that one either, but I was told early on that port 80 should be avoided.