I am a multi discipline electronics engineer and whilst radio isn't my field I have dabbled over 40 years. My 5G router is on a little shelf in the loft on an eve. I noticed momentary bursts of stronger signal when my hand was moving it to aim it. This will be reflections from my hand hitting the rear antennas and boosting reception. As a quick experiment I put a sheet of foil across joists 18" behind the router as a reflector and getting a solid 4db signal gain.
I am now thinking of a sourcing a directional antenna with a decent reflector to try. This is fun.
