Instructions
Power Cycle
Shut down your computer.
Unplug the power cable from your modem and router. Leave them unplugged for 30 seconds then plug them back in.
Turn your computer back on.
Turn on your Xbox 360 and connect to Xbox Live.
Alter DNS Settings
Turn on the Xbox 360 console.
Navigate to the right of the My Xbox tab to the "System Settings" option.
Select "Network Settings" and "Configure Network." You will be brought to the basic settings screen.
Select "DNS Settings" and alter the DNS from manual to automatic.
Connect to Xbox Live by pressing the Xbox Guide button in the center of your controller and the "Connect" option from the drop down menu.