Rick54

Which "app" are you referring to? The only way I can control any devices is through UDS Admin console on my PC on same LAN. Is that the "app" you are referring to?

Same thing here. Alexa reports "topology was destroyed"

Same issues here...

Attempting to get back to the original question here, I would like to know if anyone sells a thermostat for a heat pump system to be managed by my ISY994i that would be manufacturer supported to run with ISY994i. I have seen the posts for an additional components may be required and I don't want to add components that could fail. Reading above it appears Venstar Colortouch thermostats work with heat pumps and are controllable by the ISY994i but there is a requirement for a Polyglot nodeserver AND NodeLink. I have no understanding of these two components. I would like to have a recommendation for a heat pump thermostat that I can use. Anyone have some ideas?