The 2.4mhz band onmy R8500 keeps disconnecting every 3-4 days

Recently the wifi signal of my Nighthawk R8500 turns off every 3-4 days. Usually it's just the 2.4mhz band but sometings both 2.4mhz and 5mhz turn off. The router lights stay on and are white.

To reconnect I turn the router off then on using the back button.Then it goes through configuation then reconnects and all is good for another 3-4 days. After that if does it again and this going on for the past 3 weeks or so.

Currently my router is set using Smart Connect. I switched over to this about 4 months ago. But I never had a problem with Smart Connect or without.

I have Not added any new devices and although Windows 10 has updated a couople of times in the past 6 months there was never any issues after the updates were installed. In fact, I have never had any problem with ths roiuter until recently and so suddenly out of the blue.

So does anyone out there have an idea why this might be happening? What I can do to test to determine whether the problem is the router? or the laptop?

Thanks