I played xbox just last night, yet when i logged in today, it wouldnt let me log into xbox live. So i checked my connection which gave me an automatic troubleshoot suggestion which told me to change my MTU to auto or at least higher than 1364. I tried to, but I forgot my router username and password so I basically can't access it. Its a Cisco black router. I checked its default settings online and it should be on auto. But i dont know why it suddenly changed overnight. Help would be highly appreciated.
There is a service alert so I'd leave your set-up as it is support.xbox.com/.../xbox-live-status.aspx
XBOX LIVE Connection Advice NAT/IP/DNS/MTU/ICS/Bridging Click 4 Help