@gteagle 

The physical switching or pressing of the button will work regardless if the Wi-Fi goes out. If the physical switch is not working the wiring would be the next thing to check. I think there may be an issue with the switches themselves if the wiring has been verified.

@gteagle 

I had a similar issue with one of my switches. I have a 3-Gang box with 3 TP Link Switches installed. I could not use the outlet cover they came with so I re-used the 3-Outlet cover. On the middle switch the restart button at the bottom of the switch was being pushed in by the cover. The switch was behaving just like yours. Once I adusted the switch and cover, I have not had issues since.

@gteagle I set the switches up. The main switch controls the light. However, the second switch does only controls the whole system. The second switch doesnt really act like a 3-way switch. Thus, my review for the product is very low. Now i can only turn on/off the light from only one switch and the app. The second switch is basically useless. 

@HellBent had the same issue...last night had the idea to just loose up the screws...working great now... Took me 2 weeks to figure it out... 😅

@gteagle 

I was having a similar issue, however, I resolved it.

To properly use both 3-way smart switches in a kit you need to install in the following manner.

1. Install the first 3-way where the power comes from the breaker box. Wire it up normally, Ground, Neutral, Line/Load (the hot wire from the breaker box), and both traveler wires.

2. Do not set up the Wi-Fi.

3. Install the second 3-way switch. Wire it up normally, Ground, Neutral, Line/Load (the wire going to the fixture), and both traveler wires.

4. Return to the first switch you installed, look at the last 4 characters of the MAC address on the front of the switch. Write that down.

5. Add the smart switch in the Kasa app.  When it asks you to connect to the switch directly in the app over Wi-Fi, connect to the switch that matches the last 4 characters from step  4.

6. Setup normally.

7. Click that you have 2 switches.

8. Move to the second switch you installed and follow the directions for linking the second switch.

9. Voila!

10. Assuming that you have wired it correctly the smart switch will operate as a traditional 3-way would and will work flawlessly on the app.

I have a similar problem with my switch. Except that my second switch is powering off the actual power. So it actually kills the power to the first switch and the signal from the wifi. 

Any ideas what would be causing this?

@GarrettF so assuming I did exactly the opposite of your recommendation the first time around, how can I get back to zero and set up the switches in the correct order? I tried deleting the switches from the app and setting them back up, but it's not letting me... tempted to yank the switches back out and swap them, but that's gonna be a pain...

I'm having the exact same issue as @Justaguy.  

@gteagle this is now the 3rd time I have had to replace the switches. I have followed all the instructions and the electrician said the same that they just are defective. They work initially then completely stop working. I even took them off wifi so they would work like regular switches which initially they did, but now only 1 switch turns the lights on-off

directly.  I have RESET them now 3x and replaced them 2x and always the same issue, work for a day or two then off sync only 1 will work, or neither works.

I have another 3 way switch where I only replaced 1 of them and that one has no issues. When I purchased the 2 pack and replaced both as was told specifically for this 2 way, they don't work. I bought 12 single ones and 2 of the 3way and only issues with the 3way and 1 single was defective.