Solution #3: Place the router at eye-level or higher
From a standing position, if your router is at eye level it is probably in an optimal position to provide the best signal. I keep mine on a shelf that is above my head when I’m sitting at my desk and just below eye-level when I stand up and it works fine.
Most people don’t know that when a router broadcasts, the signal actually travels more downward than outward so the higher you place the router, the more efectively it will “rain” the signal onto the devices around it. That’s not to say it won’t go upstairs because it does also expand; it’ll just expand further if it’s set higher.