There are 2 problems, I do no know if they are related. I have installed the main and satellite switches, each one shares a box with a conventional light switch, as pictured.  The main switch operates and dims the lights as expected. The satellite switch is receiving power, as I can see the LED ring, but does nothing when I press it, whether the lights are on or off.  Since the satellite switch is receiving power and since the lights do work with the main switch, that should confirm that the switches are wired properly.

The bigger issue than the satellite switch not working is that the main switch absolutely refuses to connect to my wifi network. I follow the instructions, I connect to the switch's wifi (I need to stand within 2 feet of it to get a consistent signal), then, in the Kasa home app, select the switch model and wait for it to connect. The LED indicator then goes to blinking green, and I select my home WiFi network, enter the key, and connect to it on my phone as directs. Then nothing happens for about a minute and the switch LED goes back to blinking amber and green. On the app, it may give a failure message or it may just keep trying to connect indefinitely, forcing me to restart the app.  

I've tried this about 20 times with the same results. Solutions I have tried that haven't worked: 

Restarting the swtich.

Performing a factory reset on the switch

Moving the router closer to the switch. (It's about 15 feet away, and the wifi signal by the swich it strong)

Turning off my 5g wifi network, leaving on only my 2.4g network.

Explicitly setting my wifi channel to 1, 6, or 11, none of which have worked (the router seems to default to 11 if I set it to automatic)

I'm stumped. Any help would be appreciated.