I have a situation where an HS210 controlled circuit will randomly toggle on then quickly back off (or off then back on if already lit).  It'll do this once a day, perhaps once every two or three days.  Otherwise it works well and can be controlled by the Kasa App or Alexa just fine.

Setup is thus:

"A" side HS210, connected to a hidden wi-fi network

--> Light <-- wired in the middle (I presume) - we'll call this Kitchen

"B" side Standard lighted-3-way switch

This setup worked without fail for a few months, then about 3 or 4 weeks ago, this strange behavior started.  If I'm nearby and can view the HS210, it either looks fine, or sometimes it's gone red, or amber etc.  If red, I have to manually reset it.  Thats very rare.

I have another circuit (Hallway) that is wired exactly the same and configured the same.  It started this random toggle at about the same time, 3 or 4 weeks ago.

The router is an Archer A9, latest firmware.  No updates have been applied to suggest the firmware (router or 3way switch) may be the cause.  The wi-fi signal is near full strength according to the Kasa App.  The connection to Alexa was also disabled to ensure she wasn't sending instructions.  Only the Kasa App has connectivity.

Getting some ideas from the Forum, I have since moved both HS210's to the guest (visible) wi-fi network and will monitor. I've also had some dialogue with TP support but no sound solution yet.

Though I prefer to keep my smart devices on the hidden wi-fi, one of the feature reasons I went with TPlink, I would be content to leave these HS210's on the guest network if it solved this problem.  

Questions:

Anyone else encountering this toggle on/off situation?

Would having a 3-way lighted switch at the other end of the circuit somehow be weakening the HS210 over time to where it's starting to fail?

Would having an unlit 3-way switch make a difference?

Are there any hidden logs in the HS210 to see if it's getting outside instructions to toggle on/off?

To Do:

Monitor the situation now that switches are on the guest wi-fi.

Consider replacing the lit 3-way switch with an unlit one.

Further thoughts?