For 3 years this thermostat has worked easily and with no problems. After an internet change I was locked out of access to the thermostat. I called the Resideo Support number and had a wonderful and productive experience with the rep who guided me to an easy resolution.
I really tried to make my less than a year old Nest systems work. My HVAC folks couldn't even get it to link to the App and their online customer service was awful. So far I have found that the T6 was easy to install, you don't have to be an engineer to get it to work, and the best part - it's mostly intuitive. It was so easy to learn to use that I have never had to contact their customer service folks.
Installer tried 2 new thermostats and couldn't get it to work with the new gas pack he installed. The thermostat would like restart itself numerous times, not losing power and going blank but screen would restart itself. (like a computer restarting) Temp wouldn't hold correctly, And it would put unit in defrost mode and blow cold air and it is not a heat pump. Heat on indicator would blink. Installer triple check his readings it was set for 1 heat and 1 cool. So he gave up and installed the manual Honeywell until he got us a new Vive brand wifi thermostat. So far it is performing well.