To open the NAT to be able to connect to the server and to other people correctly you need to have the correct ports open;
Xbox 360 http://ubisoft.custhelp.com/ap...a_id/15722/related/1
http://portforward.com/ is a very good website which shows you how to open ports depending on your particular router.
Putting the console in DMZ should help, this will open all ports so DO NOT use it on PCs;
On the router there should be an option to enable (DMZ) (see router manual)
DMZ basically means "Demilitarised Zone.
This is a feature for Network Devices that need certain ports to be open. When this is set pointing to the Xbox 360/ PS3 ip address. It will basically open every port directly to the Xbox 360/ PS3.
You should go to your Xbox 360/ PS3 settings and get the IP address of your Xbox 360/ PS3. Then enable manual on IP settings.
Then in your router, enable DMZ and then enter the IP address of your Xbox 360/ PS3 in the space provided.
Then reset your router.