If you are still experiencing this issue, here are some tips you may want to try.
You can always check online services status here http://www.callofduty.com/ghosts/status
Currently the status is at Defcon 4 so you may experience intermittent issues with connecting to the server.
You may wish to check Xbox Live service status as well Xbox Live Service Status - Xbox.com
If online services are fully operational and you are still unable to connect, you may want to try the following.
- Reboot your router.
- Restart your system.
- Try using a wired connection in order to sustain the connection quality.
- To help identify if there is an issue with the router or blocked ports, try connecting directly through the modem.
- Establish a static IP address and port forward.
Here are the port numbers you will need:
Xbox: Activision Support
Should you have any questions on how to port forward, please contact your ISP or the router manufacturer.
You may also want to try deleting and recovering the profile you are having an issue with. Be sure you know your login information before doing so Delete Xbox Profile | Download Xbox Profile | Move Xbox Profile & Gamertag - Xbox.com Select delete profile only.
Hope that helps!