Comcast uplink keeps on disconnecting randomly throughout the day

Uplink keeps on disconnecting randomly throughout the day for multiple times. This will happens for 5-10 mins and then it would work fine. Since it's happing multiple times a day it drives me crazy.  I thought it might be something wrong with my modem/router so got new one. Just set up brand new modem/router, Netgear C7000v2 and still same issue even though this modem/router is supposted by Comcast.

All the other lights on modem/router are solid green but when this happens only uplink goes down and that makes internet connction lost to all my devices.

Here is the video:

https://drive.google.com/file/d/1k478Q7h8R56CpCiv7SK3QfZnRvVHehF6/view

Please help!! This is so annoying as it will cut my call when I'm in meetings or calling anyone via VoIP. When I called Comcast they are like we can send tech to take a look at this but when tech is here it may work fine that time as this happens randomly. 

Any help would be really appreciate. Thanks!