An in-depth look at the TP-Link Kasa HS210/HS-210 3-Way Light Switch. Do you have to use 2 of them on a 3-way circuit? Can you use 4-way switches for more control points? If you only use one, does it have to be in the "first" (line side) box? Do they do current sensing? What does "pairing" 2 switches actually do? What does a smart switch actually do on and with your home network? And how the heck do 3-way switches even work, anyway? To answer these questions, I tried to make this reasonably comprehensive video. Thanks to QTTechReview. Check out his 3-Way (https://www.youtube.com/watch?v=kwydife035I) and 4-Way (https://www.youtube.com/watch?v=cRohQMz8w_o) Kasa Smart Switch Videos. TP-Link's official "robo-lady" install tutorial is here: https://www.youtube.com/watch?v=ENQGH-uYk34 Thanks Geordie! 00:00:00 Introduction 00:14:53 Garage Install 00:22:32 Continuous Power Edge Case 00:26:10 Mystery Voltage On "Dead" Traveler 00:27:54 Relay State Restoration On Startup 00:31:01 Introduction to the TP-Link Smart Home Protocol 00:33:36 Controlling the Kasa with a PC using Python 00:36:11 More Current Sensing Proof: Switch Knows "Off" from "On" 00:37:54 Setup #2: More Mystery Voltage / Rebooting The Kasa 00:41:45 WiFi Packet Sniffing Kasa With Wireshark 00:44:07 Google Home to Kasa Interaction 00:46:00 Device List vs Detail View Update Speeds 00:50:43 Kasa Switch On The Global Internet: Why & How 00:53:15 Setup #3: Final Experiments 00:55:27 Two Switch Pairing / Pairing's A Crock! 00:58:15 Two Configured Kasa 3-Way Switches 01:01:27 Summary Results & Conclusions #tplink #kasa