The system was installed by a professional last week.
We installed the downstairs thermostat with no problem.
The upstairs installed and then would not connect. So we called technical support and they told us to remove the downstairs device. We did that and the upstairs thermostat installed OK.
The we went back downstairs and added back the downstairs thermostat.
Both thermostats were working and showing on the app.
Today the downstairs thermostat is offline.
The WIFI has been up and running since installation. Since the device is 15 feet away and directly in line of sight of the router, I doubt that WIFI connectivity is the issue. Why did it drop off line?
Thanks for reaching out here in the Google Nest Community.
I am sorry to hear about what's happening with your Nest Thermostat. I'd like to check a couple of things for us to further isolate the issue. Is the downstairs thermostat still showing in the app? Have you tried to swap these two Nest Thermostats? It is also possible that a network interference causes this Nest Thermostat to lose its grasp to the network. Check if there's any electronic devices near the thermostat.
The only electronic device nearby is the microwave oven. I sure hope that's not leaking radiation. Also at worst the only emissions could be from the motor that moves the turnstile. It does not seem to interfere with other devices.
Anyway I rebooted and reset everything, including the phone and my router and it has been hanging in there for the past two days.