If ever you upgrade your modem, example, to add phone service in the triple play option after going through the process of registering the new modem with the xfinity techs. BE SURE to ask them to delete the old modem details, otherwise when they run their security checks and modem validations if they have two modems listed on the account, even though you only have your new one connected, you can guarantee the check will fall back to the id of the old modem and restrict your service! This can very very frustrating as the modem web app suggests it is connected but appears to lose DNS. To resolve they have to register the new modem (again) and remove any reference to the old modem and then send a reset/restart signal to the modem. Just an FYI.