Ok, I could once play and talk with some of my friends and now I can't. My Xbox Dashboard connection thingy says I have no networking issues, and in Halo: Reach it says NAT is open and packet loss is minimal, and the top one (can't remember) is red but I think that is because I'm in Australia. I have the same problem even if I don't use my router as well, and can only play with players who I can't connect with myself if they are playing with someone else I can connect to.
Basically I need to use other players as "bridges" to get to some of my friends, even though my NAT is open.
I know their NAT isn't open, but they should still be able to connect with me as they can connect to others with open NAT easily.
This problem has only picked up in the last two weeks, and I'm not really sure what to do about it. Should I call my ISP (Optus) about it? What else could I do?
Wired Motorola Surfboard Modem
Belkin n150 "Connect" router (UPnP enabled, DMZ disabled, No port-forwarding. This router can't accept both dynamic and static IPs at the same time.)
XBox 360 Arcade (Early 2007) with 60GB Hard Drive
Optus Fusion Plan 500GB/month