Audio dropouts

Have been having audio dropouts both on live broadcast and DVR playback. Mostly live broadcast. New home, fiber optic, all WiFi system. Had a tech visit 3 day ago who said it’s common with the set top boxes, not the router. Replaced the set top box and HDMI cable. Good for a couple days, but watching the KC NFL game, it’s back. It’s also on the other TV’s in bedrooms. 

Rebooted router, set top boxes, and system refresh on the TV set top system. (Done this 10’s of times to no avail).

Back to square one. Although I’ve read on other forums that Cox’s translation of the incoming signal formats is the likely cause. However, it was also said that Comcast has the same problem. But, we just came from XFINITY land after years, and never saw this or the other problem(s) we’ve had with Cox. And, we had coax.