You can have PFSense act as an access point if you install a Wifi adapter in the box you use as a router. Depending on the square footage you need to cover, you

You can have PFSense act as an access point if you install a Wifi adapter in the box you use as a router. Depending on the square footage you need to cover, you might not need anything else. Edit: Just saw the bit about thick walls. Sticking to 2.4 GHz might have a better result if your neighbors aren't too close.