It sounds like the OP & @Echolane are based in the US, so the BT solution is probably not available there.
+1 on the Ubiquiti solution - I’ve just installed their UDM (and switch) and now have excellent coverage - I can add extra WAPs if required as well. I’m in the UK and am using the DrayTek Vigor 130 modem to feed the UDM router with much success.
George.