(I've read the sticky and tried everything..nothing seems to work at all)
What Country/State/Province do you live in? US/AL
Modem brand & model number: (This is a router & modem combined) 2wire 2701HG-B
Network Connection Type: Wireless
If Wireless, what type of encryption are you using? WPA-PSK
If Wireless, are you using a white or black external adapter, or an internal (Xbox 360S) adapter? External adapter.
Things you have tried: I've tried portforwarding and mac filtering and enabling my 360 directly to the router via ethernet.
Is UPnP Enabled? Unknown
Is NAT Type Open? Yes
Any Error Codes you encounter: None.
What type of internet do you have? DSL
Who is your ISP(Internet Service Provider)? AT&T
After you run "Test Xbox LIVE connection" and click on "More info", what is the exact message shown on screen?
"Your network doesn't have a sufficient MTU setting. Xbox Live requires a minimum MTU setting of 1364.
On your PC, go to your router configuration webpage and set the MTU to auto or, the MTU to 1364 or higher. If that doesn't work, disconnect your console from the router and connect directly to the modem.
Get help with MTU settings at xbox.com/network help.
Have you corrected your router's MTU settings, or are you directly connected to the modem?"