My Father in Law and I both have ST installed, and use Alexa as a voice control. He needs to be able to enter our house when we are on vacation, so we added his cell phone to our ST so we could use it as a presence sensor and it would deactivate the alarm when he arrived.
We had been having all sorts of problems with devices randomly turning on and off, and I had been tearing my hair out. The device history would always say “light turned on by Alexa” I had even posted on these forums, trying to figure it out.
After a year of dealing with our issues of random device activation, my FIL called and asked me to come over and help him figure out why he had no control over one of his lamps. Looking at our phones side by side, I finally realized what was causing the problems.
Somehow, the Alexa in his house had discovered the devices in both houses, even though the Alexa at each location was attached to different accounts. The ST app only showed the devices installed in each location, but the Alexa devices were controlling the devices of either house.
Since some of the ST devices had similar names and my mother in law can’t ever seem to remember what a device is called, she would yell out random device names that sounded right to her, until she got what she wanted: “Alexa turn on the lamp.” then “Alexa, turn on bedroom light,” etc.
When the names she was shouting matched one at my house, the lights in my house would turn on.
I solved it by removing him from my ST app, and we haven’t had a problem in weeks. Now I just have to figure out how to let him in the house. (The key fob presence tags don’t work for us)