Why does my wireless router disconnect when I turn on my cellphone's WiFi?

Solution 1:

I had the same problem, my wife's Samsung S4 was taking down the network. Several other devices connected without issue including my cell phone, but for some reason her phone crashed the network when she turned Wi-Fi on and connected to the network. We tried many things which did not work, and in our case the solution was to create a Guest Zone on the router to which she connected with her Samsung S4.