I’m also on Android. I have excellent connection on my phone and two Ring cameras that are further in distance than where the controller sits. Fifteen feet from my router I had an rssi of 77, which seemed really high. But my external Ring camera, which sits outside my house, behind two metal garage doors and up on the eave of my house has a rssi of just 65 (lower being better). Go figure.
I put the controller on the garage wall where my RainMachine connected just fine, and it can see all of my SSIDs, but fails to connect to any of them. 5ghz or 2.4ghz, doesn’t matter.