WiFi signal drops

I can't seem to go more than about 12 hours without seeing that any of my household connected devices (two iPads, two iPhones, my Mac) all are on channels other than the ones I set them on.  It appears that the router is randomely and frequently dropping signals, leaving the devices to search for the next available one.  

I've got a Nighthawk R8000 using Firmware V1.0.4.68_10.1.75 (should be the latest).  My devices are all connected wirelessly and not via ethernet.  

This seems to be a commonly reported problem on this discussion board.  Despite the proflic number of complaints, the recommended solutions don't quite apply to my situation, or are from years ago with older firmware versions.

I did just try doing a factory reset using the reset hole in the back of the unit, but that hasn't helped.  

Please share any thoughts/solutions you may know of.  This is super frustrating!

Thank you!