I seem to be having the same issue that several other posters have had: once installed and energized, the smart switch goes on and off continuously. However the solutions offered for them don't seem to apply in my case.

The switch is a single pole switch controlling a light, and the only switch on that circuit.

The old dumb switch had a ground and two hot wires connected to it. A (white) neutral wire was in the switch box but was not connected (capped with a wire nut). I used the neutral wire to connect to the Kasa switch's neutral and connected the two load lines and the ground.

It seemed very easy. When it was powered up I easily connected the HS200 to my WiFi network, but when I turned the device on via Smartphone it started cycling continuously between on and off. I double checked all the connections and all were tight.

I'm at a loss. Can anyone provide advice?