Just under 4 years ago, I bought 6 TP-Link/Kasa HS-210 (three kits, two switches per kit.)
In the last month, 3 of them have failed. TP-Link says the warranty has expired, so I'm out of luck. I'm glad I hadn't bought more!
Searching shows that these devices are failing a lot. Since TP-Link won't stand by their product even when it's clearly flawed, I won't be buying any more of their products. I sure am glad I'm not a contractor using their parts in many homes!
BTW, I called customer support (the chat was down -- these things happen) and the customer support rep communicated well and was helpful in exhausting the possibilities to revive the device, leading to the conclusion that it failed, and opened a support case to replace them (though I had made it clear they were nearly four years old.) My case was closed due to being out of warranty. If it was just one unit, no problem (frankly, I just threw the first failed one away. I wasn't concerned until the failures started mounting up.)
When the first one failed, I bought another kit. I guess in 4 years I'll see whether they improved the product. But for now, I would suggest avoiding it.
I have quite a few other TP-link devices (KASA smart plugs) that have been reliable, but still I'll find another manufacturer for my future smart home updates.)