C6300 disconnects every 1-2 hours requiring reset...Comcast

Hi. Read through other threads and found no resolutions.

I am on my second C6300 router. I thought these issues were isolated to the first router, but the second is having the same issues. 

Comcast came to our house and verified signal strength, hook ups, etc. Problem seems to be isolated to the router/modem.

Issue: Router will drop WiFi service every 1-2 hours. Signal can only be detected by devices if router is reset. I followed recommendations to modify the DNS, change channels, etc. with no help. I have the most current firmware. All lights are lit when the issue occurs. Multiple phones and computers are no longer able to detect either 2.4 or 5Ghz signal.

Any suggestions?

Edit...I was able to connect to the internet using an ethernet cord; however, I sold my old computer and no longer any any devices that have ethernet cords to check connection status without WiFi.