I tried with my phone to control HS300 with kasa app, Of course wifi off, and 4G on. It works, this means remote control is enabled. Just firmware or cloud service problem, I think.

I tried everything in the link for more than 30 times, I even changed brand new battery, but still arrival sensor doesn't pairs.

Deco app displays smartthings arrival sensor is compatible with M9 plus. But So many times tried to pair but M9 never dicover the device. I can tell arrival sensor trying to be paired, but deco m9 is...

I'm using M9 plus. Deco app version 1.81, I had no problem, but 1.82 is problematic for me. 1.81 I could turn on off any tp-link smart devices, but 1.82, everytime I tried to turn on power strip...

The link you gave me was same one from tp-link support, and I tried that about mor than 10 times but had no luck.

No, Alexa app just can't recognize my four HS300. But there was no error message at all.