I got a NetGear wifi range extender in the hopes of extending the network out into the yard more. Set up is pretty simple in the directions: plug it in, press the WPS button, press the WPS button on the router, and done!
How to a wifi range extender with Apple Airport Extreme
The Apple Airport Extreme doesn’t have any buttons on the back (this is the tall version with ac). The way to get around this is out by pretending to add a wifi printer to the network.
Open Applications/Utilities/AirPort Utility. Hover over the Base Station option and Add WPS Printer is the last option on the dropdown:
Press the WPS button on the extender, then select First Attempt in this menu: