Issues after upgrade to xfinity advanced modem.

Ever since upgrading my modem I get periods were I am unable to reach the internet from wired and wireless devices for about 5-10 minutes at a time. Seems to be when we have more than 1 device using the internet at that time. Anyone else run into this upgrading from the standard modem? One thing I did notice is the new modem seems to get pretty warm.

Thanks,
Dan