A friend convinced me to get an XBox 360 about 7 months ago. I'm really glad I listened, because I have a blast gaming on it. I never thought I'd enjoy online gaming, but with the right people, it really can be a lot of fun. There was just one minor downside to this that I discovered about a month later-- I couldn't game or talk to some people on the XBOX Live network. Now that might not sound like a big problem, but it can be. You can't hear certain people in the game unless you join a party hosted by someone else, heck you can't even join the same multiplayer match unless someone else hosts it. If you like gaming with the person that can be a huge problem.
Well, it was a bit of an annoyance for some time, but we just got around it by having someone else host the games and join a party so we could hear what the other was saying. That worked well enough...until I got "Red Dead Redemption." If you invite someone to your multiplayer session that you can't connect to, it boots one of the "incompatible" players. Not much fun at all. That led a friend and I on a search as to how to fix that. He found a video that got me started in the right direction as to how to fix it. Well, after a few failed attempts, I got it sorted out. Here's how for those experiencing similar issues.
1. Opening ports is definitely the first place you want to start. It's not too difficult if you have a router that lets you forward ports. Portforward.com is a great place to learn from. You'll need to forward or open the ports listed on the XBox Live site-- basically TCP 80, UDP 88, TCP/UDP 3074, and TCP/UDP 53. Test the connection. It should tell you if you have a strict NAT or not when you test you XBOX Live connection (it won't always tell you and I'll explain that later). If you can connect to those you haven't been able to, then huzzah! :D If it doesn't work, you can try setting up a DMZ for your XBox's IP address. As for how to do it (if the router is capable of it), you'll have to look at the router manufacturer's site or google it.
2. Well, I tried the above and it didn't work for me. XBox Live said the connection was fine, but I still couldn't connect to some. I figured "aww, screw it" and decided to connect directly to my modem, no router involved. I tested the connection and lo! Strict NAT. I get my internet through CenturyLink (formerly Embarq and CenturyTel). Apparently, there are XBox Live compatible ISPs (nuts, I know) and the modem I have through CenturyLink (a 660R) apparently causes trouble. After a bit of googling, I found that I didn't need to get a new modem, I just needed to put it in "bridge-mode". Bridging the modem was a piece of cake. MUCH easier than forwarding ports even. I don't totally understand how it works, I just know that it did work. ::LOL:: Sorry, this isn't really an exciting post, but I'm hoping that it helps someone else out. It's a flipping pain to search most of the known web and not find what you're needing. I'm one of those "hands on" people. I look at the piece of tech, goof with it, and sometimes I can get it to do what I want it to. If you have questions, I'll see what I can do to help. The links should help point you in the right direction though. :)