Instructions
Reset all of your network components. Turn off your Xbox and computer and unplug your router and network modem. After 30 seconds, plug in the modem and let it initialize. Plug in the router and let it initialize. Turn on your computer and then your Xbox.
Reset the Xbox's network settings. Select "System Settings" from the "My Xbox" tab, choose "Network Settings" and select "Wired Network." Press right on the D-pad and select "Restore to Factory Defaults." Confirm "Yes" and the system will be reset.
Open the ports that Xbox Live uses on your network modem. Refer to your modem's manual for specific instructions on how to access the modem's settings and open ports. Open ports "UDP 88," "UDP 3074," "TCP 3074," "UDP 53," "TCP 53" and "TCP 80." This will ensure that your modem's firewall will not block the console from connecting to the Internet.
Connect the Xbox directly to your router or modem. If the other solutions do not work, try connecting the Ethernet cable directly to your router or modem to get a direct Internet connection.