My Archer Axe75 (Axe5400 Tri Band 6E) has been dropping internet signal randomly over the past couple of weeks. It will run for a couple of days, and then no internet. The front panel internet indicator switches to yellow, and we're offline. Local wifi network access is not affected. My NAS, and file transfers between devices still spark as they should. Here's what I've done to troubleshoot so far:

1. When the router shows no signal, I've connected a laptop direct to the modem, with the same cable that usually connects to the router, and have full speed internet on the laptop. Shut down the router for 10 minutes, rebooted, and internet works. 

2. Internet failed again. Replaced Cat 5e cable between modem and router, anyway, with a known and tested cable. Shut down the router, rebooted, and we're back in service. 

3. Internet failed again. Did a factory reset on the router. Checked to be sure automatic firmware updates are switched on. Rebooted, back 

Then lost internet yet again. I rebooted, and got it back. 
 

What's wrong with this thing? I'd appreciate a solution, because right now it looks like I'm buying a new router - definitely NOT this brand.