I got two Leviton VRMX1s paired to the C-8 Pro. One them did what it's supposed to in a RM automation last evening. But using the GUI with the C-8 Pro in my office, they are both unresponsive. If I take the C-8 Pro out into the kitchen, where it's within 20 feet of the Levitons versus 30+ in my office, they work fine. There are 800-series dimmers all around them. I would expect enough meshing to go on that they'd be reachable from most anywhere. The VRMX1s are on the supported list.
Suggestions? I would have expected these guys just to work.
You might want to check to see if your 800 series dimmers are functional repeaters/range extenders. Remember that distance is not the only factor affecting connections. Things like water piping, HVAC ductwork, appliances, brick walls, etc. can block the connection.
I have some Z-wave motion sensors on my deck, It is only 20 feet from my hub. However, there is a brick fireplace directly in the line of sight. In order to get the sensors to connect, I had to add a dedicated Z-wave range repeater. I have used both Ring and Aeotec range repeaters successfully. Just make sure you have line of sight from the hub to the range extender and then line of sight from the range extender to the VRMX1s.
Ideally, you want your C8 Pro hub to be as centrally located as possible in your home. If your office is at one end of your home, you might want to relocate it to a better location.
