@septer012 this is all very good.

I am a DIYer... just moved into a home that has an extraneous amount of switches controlling the same light (4-way system). I just need a single kasa dimmer switch (HS220) to work, let me know what you think about this plan:

I was going to close off both of the 3-way switches and make them permanently "on".  To achieve this, I would combine one of the travelers with the load wire, and then cap off the other traveler; this would make the switch permanently "on".  I would repeat this for the other 3-way switch.

Then I would take the 4-way switch (double-pole), and convert to a single pole (ehow website has a good article that I can't directly link in this forum), and install to HS220.

What do you guys think?

@AustinTX all I would suggest is that you check the load side three way is indeed programmed and powered up not red LED or powered off.  You should also have only one entity for the switch in the kasa app while both switches are powered and not red.  If you have an entity for ea h three way that's not correct. 

@Chicago_SH 

Thanks for all the guidance...I have now installed a 6 way switch (5 switches and outside lights).  Followed the guidance in this and previous posts, and the wiring aspect worked immediately.

However, I encountered a problem running a schedule with the App...tried on at sunset off at sunrise, specific time on and off, etc and lights would turn on, but would never turn off.

Chatted with Kasa support, and they had me reinstall app....didn't fix it.

Finally, for some reason decided to set 2 time "on's" instead of a time on and a time off.   And that worked....so now, for example, have schedule of lights on at sunset, and again lights on at sunrise....and goes on at sunset and off at sunrise.

No idea why this works...or whether I have a faulty Kasa switch, or whether it is an App/software issue.  Seems it should be an issue for 3 or 4 way switch as well, but assume no one else has experienced since no posts to that effect.

I built a test rig to test this works, before i installed it in my house.  It works just fine, as long as you replace all both three-ways and ignore teh four-ways it will work.  Another place of contention is you need to porgram the power side three-way first as the primary, and the load side three-way as the secondary. 

Google implementation also works well to control this setup.

@toddg 

you need to connect both travelers to the HS210 switch make your 4 way switches operational.

@JRJinYYC 

I have a 4 way switch.  I tried to install the Kasa 3 Way Switch in 2 of the switches.   I setup WiFi and paired the light.  I had one of

my hallway lights that came on but very dimm.  I could not get the kids them to turn on or off with app or on any of the 3 switches.  
 

Here is the weird thing.  
 

Switch 1 downstairs has 4 wires.  
 

Black, White, Red, Green

Installation was a breeze but still not working. 
 

Switch 2 Master Bedroom has 

Black, Black, Red, Green (these 4 were used in old switch but there were more in junction box)

I had 2 whites that were together with wire nut

I had 1 white and 1 black that were together with wire nut. 
 

I tried to connect the new 3 way to this switch. 
 

I put black to black.  I used the black and red as the travelers, I connected green to ground,  I connected white to the two whites that were wire nut together. 
 

Switch 3 I did not touch.  It does have multiple wires like Switch 2.   
 

How do I got about configuring my 3 way Kasa Swirch to work?  
 

Thanks in advance.   

@Chicago_SH 

hoping for clarification on the 4-way (or 5-way) switch setup using HS210kit at 3-way switch locations.

The hs210 has 2 traveller poles, and 1 dual pole for line/load.  Did you only connect a single traveller to each hs210 in your 4-way config with a traditional 4 way switch in the middle?

thanks

CONFIRMED WORKING FOR BOTH 4 AND 5 WAY INSTALLATIONS IN MY HOUSE.

I can confirm that a single HS210 kit (with 2 switches in it) worked for both my 4 and 5 way switch configurations.  They should be installed in the "3-way" switch boxes present in each configuration.  I'm not positive which boxes those are or exactly the layout of the wiring as my electrician installed them for me, but an electrican can tell you.  Basically the 2 boxes with the least wires in each case.  For the other switch locations you use normal dumb switches (the Kasa switches will know the on/off state from the presence of power at one of the switches).

A KEY POINT: In order for this to work correctly, you have to set the switches as a pair in the software.  This means you only add ONE SWITCH initally, and then you must choose the "installing 2 switches" option during the set up of that first switch.  It will then have you go to the second switch and hold the button down till the red light flashes.  Once this is done, the two switches show up as a single switch in the software.  They are then able to communicate back and forth if they see power and thus mark the switch as on or off.    If you fail to do this, you will have a number of issues related to turning the lights on and off programatically.  If you do this wrong and you see two switches listed in the software, you must go back and delete both switches and start over.

Great job TP-Link for such a flexible product.

@board4mic So at the risk of sounding obtuse, the 1 regular 4-way and 2 Kasa 3-way swicthes works exactly as one would hope:

The app knows if the light is on/off 

The app correctly turns on or off as per request/

Any switch can change the state at any time

Correct?

And thus, in the case you wanted to have 4 or more stations, all the addditional switches would be 4-way?