yeah my NAT is set to moderate, it cannot be changed from the dashboard, cause I tried. I find matches fine, and I've been able to play with all my online friends fine. But for some reason I cant join any of my real life friends party's.
After the 360 hit the market most router companies have been very supportive of Xbox Live given it's success and pending their further success, if you catch my drift. My router is an old Netgears router and even they supported them (their older models, 2000 yr. models and up I believe). Anyway, most companies have released updated firmware for their routers to be able to properly handle Xbox Live and everytime they do update your routers firmware, it's advised that you do in order to keep the settings they have with Live up to snuff. If your router's firmware is current then try just resetting your router with your Xbox 360 turned on.
I always had a strict NAT rating but I never wanted to dabble with my router settings because playin' some games, to me, was better than screwin' up my entire internet connection. Well, with the latest Xbox Live update Lost Planet was havin' trouble holding people in match lobbies (after you went from the main lobby) but it was the only game. It's my main game so I took it to heart D: I read that if you had your routers current firmware it wasn't an issue but only an issue for those of us who didn't. Well, I updated my firmware which helped my LP issues and on top of that I noticed my new NAT rating was set to Open. Many joys there as my join list grew, big time, for every game I played.
Now, after I got Halo 3 home and booted up I got a message, when I joined matchmaking, telling me my NAT was set to Moderate and it could cause issues connecting to matches. I passed it off as a game bug and played some matches with random people. Played a few matches then got an invite from a friend of mine and I couldn't join so I knew there was a problem at this point. I went to the Dashboard to test my connection. Oddly enough, my NAT had changed from Open to Moderate just from booting up Halo3, somehow. Knowing I had the most updated firmware for my router I thought I'd give the only thing I knew further how to do a try. So I reset my router, mistakingly leaving my Bawx on (you may have to turn it off to make it work, I have no idea), and retried the connection test. To my surprise my NAT had returned back to Open and I was now able to join my friend's match.
So try both of those and hopefully they'll help you out. If not, I tried, man
Chas, that's odd I guess. I don't know what the problem could be and I can't find a post on Bungie's clusterfuck of a Halo 3 forum addressing it so it must be rare if not just only me. I've had no problem gaining the skull, campaign level/beating the game, needler, etc. achievements so I don't get it. Oh well, maybe it's like the "Seriously..." achievment with Gears and it'll eventually decide to register.
