Internet Connection Disruption

My modem shows many unicast errors:

Started Unicast Maintenance Ranging - No Response received - T3 time-out;

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;

16 consecutive T3 timeouts while trying to range on upstream channel 0

We lose our internet service for 5 - 10 minutes several times per day.  Xfinity says no outages are detected.  

Has anyone here had similar problems and got them fixed?  I have seen many people had the same issues, but not many who got it resolved.

Your comments / feedback would be greatly appreciated.

Thank you,

S