Are you able to make any suggestions? The problem persists on the Firestick but not on the Shield.

Yes, it's an Nvidia Shield. It's only a year old.

I've had a Duo, for about 1 year now, hardwired to my router, and it runs flawlessly on my primary TV. I use it only to watch local TV stations. I have a second TV that runs HD Homerun on a Firestick connected by WiFi and it has also run flawlessly until recently. It works well for a certain amount ...