I have a problem with Halo 3, when i try and join a party a message comes up?

[Carnage]

It says that I am running the most compatible blah blah, which is OPEN NAT, what the hell is OPEN NAT and how can I stop it from stopping me joining?
well my friends tried loadsof things like inviting me and stuff

 

[Stunna Love]

i have gotten that message several times but i think it means that the party isn't there anymore if it is there just tell your friend to invt you to the party.... P.S. the party isn't there for me when ever i get that message

 

[G Joe]

Your NAT status has nothing to do with the game or your 360, it's all about your Xbox Live (network) connection.

There are three types of NAT connection settings: Open, Moderate, and Strict. You probably have either 'moderate' or 'strict' NAT settings, meaning you won't be able to connect to other players who are using Strict NAT settings.

I hope you'll understand this thread I'm giving you, because it explains everything about NAT connections, and how to change them.

http://www.rat*******s.org/viewtopic.php?t=32

If you don't understand anything about network connection, get some help from someone you know who does, or call a technician if it's that crucial.

Good luck.