You are probably in the US. In Germany usually each radiator has a thermostat and you usually do not have wall thermostats unless you have floor heating.

That being said, I’ve double checked and it is Netatmo [0] and not Nest. The point still stands, that some cloud based home automation devices behave stupid if they cannot talk to the server.

[0]: https://www.netatmo.com/en-gb/additional-smart-radiator-valv...