Random drops for two or three minutes

Two weeks ago it started dropping five or six times a day.  All devices are affected - wired and wireless. 

Scheduled a service call since the person in the chat said they detected line issue.  A day later they canceled the service call stating they found the issue and fixed it.  A week later it's starting again.  I don't feel it's a coax cable issue.  The lines are underground to the house and only a single line to the office.  No construction or anything to disturb the lines at the house.  Ping is fine, speed is fine.  I would expect a cable issue to be a consistent problem not random. 

Next they wanted to sell me a new modem.  I don't see any reason for this modem to start randomly disconnecting.  I've had this Hitron CODA56 for seven months with no issues.  Everything is locked down in the modem, so not much troubleshooting in the device to look at.

After that, they suggested changing my internet plan.  I don't see how changing plans would have any affect on a disconnection issue, but I'm not that familiar with how the system is setup on the xfinity side.