How far away is it? thats kind of the key. And what are the exterior walls made of? thats also key as certain materials can block wifi very well.
Are you able to pick up a signal and have decent performance where you'd be putting the extender? They need a decent signal to connect to and rebroadcast.
Ideal setup? just run a cable from their home to yours.
the other option I'd recommend if this is goin to be your primary setup would be to get a triband extender. A standard (dual band) extender has to receive and then rebroadcast with the same chip. And it can't do both at once. So its performance is half of what its getting. Versus a triband extender has a 2nd 5ghz chip just for router----extender communication.
