@Zoidybergur I think you're on to something as my traveler goes from my house to a detached garage and powering a LED light fixture. I ended up getting a 2nd HS210 for the other end and everything...

I installed the HS210 3-way switch and it's working physically just fine at the switch and also at the other end using a standard 3-way switch. Using the app the switch turns on just fine but takes 2...