Smart Radiator Thermostat wireless reachability

Options

Hello I have 2 floors (ground and basement), each with zone valve and hence I need 2 Smart Thermostats.

At the moment I have 1 Smart Thermostat + internet bridge at ground floor and I need to buy an additional Smart Thermostat for the underground basement. I am concerned about the wireless signal reachability for the Smart Radiator Thermostat in the underground basement.

Question: are Smart Radiator Thermostats communicating with the Smart Thermostat via the Internet bridge ? in such case if the Smart Radiator Thermostat in the basement cannot reach the Internet Bridge how is it possible to extend the signal? from the ground floor?