THINGS TO TRY
1. If you are using an Xbox Live-compatible device you should not receive this error message.
If you do have an Xbox Live-compatible device, follow these steps:
a. Visit the following Web site to determine whether you have the correct firmware version that has been certified as compatible:
http://www.xbox.com/en-US/live/connect/routerlanding.htm (
http://www.xbox.com/en-US/live/connect/routerlanding.htm)
b. See the router or gateway instruction manual for information about how to change the MTU setting.
2. If you share a connection with a router and a modem, try a direct connection without the router.
Note This eliminates any router configuration problems.
a. If you can connect without the router, you may have to set the MTU on the router to 1364. To do this, or determine whether your router supports this feature, see the router support documentation or contact the router support group.