hashbrown: If this is for desktops I suggest a USB extension cable and blu-tacking the adaptor high on the wall as a cheap way to improve reception. If that works then an extender in those locations should give your mobile devices better coverage too. I'd avoid the wall wart units and get something with diverse antennas that can be wall mounted. Some have Ethernet ports so they can do dual duty, supply the desktop via Ethernet and acting as an extender for mobile devices. READ THE MANUAL BEFORE BUYING and ask some questions here if your unsure about that path.
When the RBI was first installed, I bought a couple of usb adapters for the desktops and did a lot of experimenting with placing them in different locations on an extension cable and also trying a variety of parabolic reflectors to focus the signal. The parabolic reflectors definitely help but they don’t seem to help quite enough and any point I can reach with the usb cable doesn’t seem to make much difference either. Ultimately, all attempts to improve the signal failed to achieve the result I needed and after many days of trying different things and building different reflectors I gave up in frustration. That is when I started looking at powerline adapters and wi-fi extenders. So far the whole experience has been pretty discouraging. The only good connection I have is an Ethernet cable running outside up to the router. Unfortunately, this is just not a practical option for the whole house. I have multiple computers in my room and I can’t run separate cables to each of them and I don’t want to have to keep unplugging and plugging the one I do have. We also need connectivity at the other end of the house for the laptops. I’m racking my brain to work out the least awful solution but so far I don’t really know how to fix this. Hence my questions (and gratitude for the attempts to help).