Restart your stuff like unplug ur modem or router either one to reset the connection and then give it about 5mins to plug it back in and then it should work when u unplug the modem or router make sure u unplug ur Xbox to and then plug it all back up to restart the connection
If you get the stuck at joining bug.... use the home button and go out to dashboard... open dash select settings.. scroll down to all settings. Select network settings scroll down to disconnect from live and select it.. wait for No services available in the status.." then select connect to Live... wait for All services availabletimes and you should be back in the game and on the loading splash screen..
U see the searching thing u have to wait for it to say refresh and maybe it will work then or while its doing that go your setting hit offline wait a few then hit online and try again