I've never successfully made WiFi extenders work correctly. So I actually solved that problem by creating two separate networks in my house. I have a cable modem connected to a WiFi router that assigns IP addresses in the 10.1.whatever range, and I have a cable running from one of the WiFi router's ports to a second WiFi router that's set up as its own separate network (it assigns 192.168.whatever addresses). So traffic isn't routable from a device on one WiFi network to a device on the other, but frankly, I don't care. It's been way, way more reliable than trying to set up an extender.
