I am a Which? member. I will contact them and see what they have to say
about this issue. My Nest is a 3rd generation too, I think. They used to
have a good phone help service, as I remember but now it's just a
messaging service. Pretty shabby!
I have exactly the same issue. I found an article on the Which? Site
which stated the Nest is withdrawing app support for Nest thermostats
from 25th October 2025. If you look at the sctual thermostat it is still
functioning and you can still control ...
