CT100 thermostat loses connectivity

I have five CT100 thermostats around my house, but one in particular keeps losing connectivity to the hub. It claims to have a connection on the device, but is neither reporting its current values nor accepting the ones I’m setting.

Does anybody have suggestions for how to debug it?

Here are a few things I’ve tried/checked so far:

  • On graph.api.smartthings.com, it is listed as inactive.
  • I’ve tried it with the default CT100 device type, as well as RBoy’s custom handler (which works great for all the others)
  • It’s in an area with plenty of other powered Z-Wave devices, so signal shouldn’t be an issue. I’ve repaired the network a number of times.
  • As a thermostat it seems to function fine, it calls for heat properly and so forth.

Any debugging pointers would be appreciated! Given that 4 of 5 working, I also have to consider the chance I’ve just got a bad device…