tl;dr: If you are having problems with the Kasa three-way switch in a four-way circuit where the Kasa app and Alexa don’t see the right state of the circuit (on/off), make sure you replace both three-way switches in the circuit with HS210 switches. That will fix the problem.
For a change, I’m writing about some home automation adventure and not about Computer technology. I’ve been slowly replacing our regular switches with TP-Link Kasa switches – in my opinion, these switches are easy to install, solid (stay connected and respond well), the Kasa app is simple and functional and the integration with Amazon Alexa is great.
In order to keep costs down, for three-way circuits, I typically buy the HS210 kit and then replace just one of the old switches with a HS210 switch. This works fine with the Kasa app and Alexa all recording and reporting the status and toggling the switch state correctly as well as both three way switches (the HS210 and the regular switch) control the circuit as before.
The problem I ran into was with circuits that had four-way switches in between – I have two at home, one that has one four-way switch and one that has two four-way switches and each of these had two three-way switches at the ends of the circuit. When I replaced only one of the three-way switches I ran into issues with the Kasa app not showing the right status and Alexa not able to correctly control the circuit – the physical control from the switch worked fine but to toggle through Alexa you try one command (Alexa, turn on lights) and if it didn’t work then try the other (Alexa, turn off lights) and essentially it causes the effect of toggling the switch.
That bothered me – so this weekend, I read up a bit about how four-way circuits worked and how the Kasa switches worked and I figured replacing both three-way switches in the circuit with HS210 switches should fix the issue. I did that with both my four-way circuits, removed the existing configured switches in my Kasa app and added them back again as pairs and it works flawlessly now. Mission Accomplished! 🙂