I was called in to check on a friend’s WiFi setup. I couldn’t get it to work, and finally told him it looked as though the wireless on his router was fried. I asked him to check the router and continue troubleshooting.
He roped in a friend to help him, and had the friend set up the router at his place. It worked. They took it back, it didn’t work. So obviously, the wireless wasn’t fried. Something was wrong with the location.
So they removed power to circuit after circuit in the house, before walking into the living room. The friend asked “What’s that?”, and pointed to their wireless Audio-Video link. It connected the TV in the living room with the TV in the kitchen, so they didn’t need more than one set top box. When they powered down the AV link, WiFi worked.
They solved their problem by setting the AV link to another frequency. It had a choice of four settings. It had been set on one, and that was apparently the same frequency as the Wifi router.
So, AV links can create interference that makes your Wifi router seem dead. Food for thought!