Update: Our shop wifi died mid quote last Tuesday and I stopped trusting the router
Last Tuesday I was on a call quoting a 3 bedroom move to a couple in Sacramento when the wifi straight up quit on me. I ran to the back room, saw the router blinking orange, and did the usual unplug for 30 seconds trick. That only bought me about ten minutes before it croaked again, so I grabbed an old ethernet cable and wired my laptop straight in to finish the call. Turns out the thing had been auto rebooting itself every few hours for weeks and nobody noticed because we mostly use phones. Now I want to run cable to both desks, so what are you all using for small office setups that won't flake out?
Saw a thread on a tech forum where a guy traced the same random reboots to his router's power brick going bad, not the router itself. Cheap wall wart was putting out low voltage and the thing kept resetting to save itself. He swapped in a $12 replacement and it ran fine for years. Before you rip out all the walls, check if your router is plugged into a power strip with a bunch of other stuff, since that can also cause brownouts. What router are you running right now?
Learned this the hard way last year when my router kept dropping every time the microwave ran, and I spent a whole weekend blaming the cable company before my wife pointed out the obvious power strip situation. Turns out I had the router, a lamp, a phone charger, and a space heater all fighting over one cheap strip, which is basically me asking for network problems. Moved the router to its own outlet and the drops stopped that same day. Your point about the power brick going bad is a good one too, those cheap ones do wear out and cause all kinds of weird behavior that looks like something else. I am running an older Netgear Nighthawk that has been solid otherwise, so I am noting the replacement brick idea in case it starts acting up again. Checking the simple stuff first beats tearing into walls any day of the week.