go test your connection

if you disconnect from your router from the actual xbox settings and reconnect, your nat type will go to open, i had the same problem but this solved my problem and now my nat type is always open
i think it was to stop the prestige glitch

Got 2 360's and one is always moderate, no matter what I try the nat type will never go open.

The times it has went strict rebooting the router has changed it back to moderate.

PlayerOne wrote Got 2 360's and one is always moderate, no matter what I try the nat type will never go open.

The times it has went strict rebooting the router has changed it back to moderate.

This is a common issue when running more than one xbox on one router. I managed to fix this a while back but can't exactly remember how I did it lol. Try looking it up on google

Are you wireless or wired? Test your connection, and follow all the instructions your Xbox tells you. Come back here if you don't find an answer.

go to test connection - test it - sign in - go on mw3

Reset all routers and xbox worked for me ;)

either another device grabbed the local ip that has the ports open too check take every thing off the network (pc,laptop,phone,etc) allow the 360 too connect after u turned it off, and see if ur ports are open if not then u can log into the default gateway (ur router) by typing the ip address into the url bar in ur browser 192.168.*.* and log in with either the dfault pass (admin),or what ever u have set it as and then look for ur 360'ip in attached devices lock its mac address to the ip then go too port forwarding and type in ur ip form the xbox and open port 3074 udp/tcp u need both then save turn off the console and router , wait 10 sec turn router on then console

Test your Xbox LIVE connection and it will tell you to re start your router.
Restart your router and test your connection again and it shouldn't come up with a error and your Nat will be open.