|It's possible that your router is blocking the ports to work Xbox Live. Go into your router settings and look for "Port Forwarding". With some routers such as BT it has pre loaded profiles already on there in which you can choose the profile and apply the changes.|
To be able to get into your router settings go to Start > Then in search box type in run. Hit enter then type in the dialogue box cmd and hit enter. Type in the command prompt box "ipconfig" then hit enter.
Once you have done that look at your Default gateway address, this is the address of your router. Put that into the webpage and hit enter. You will be prompted for a username and password which should either be somewhere on your router or you can call up your ISP and ask them what it is.
Look for a tab or section where it talks about Port Forwarding, it may be in some advanced settings somewhere.
If you need anymore help just write back to me
These are the ports that need to be forwarded in order for Xbox Live to work:
Port 88 (UDP)
Port 3074 (UDP and TCP)
Port 53 (UDP and TCP)
Port 80 (TCP)
Hope this helps.
Get back to me with the outcome.