The Airobot thermostat and the Airobot ventilation device (only the ones with the V02XXXXXX serial number from 06.2021 onwards) can connect through the Airobot server. You have to have the internet for that. Both of them need to be in the same homegroup on your Airobot mobile app. Then, the ventilation devices start picking up CO2 readings from all thermostats. You can set a CO2 limit. The Ventilation device operates from the readings it gets with the lowest set CO2 level. It keeps every room with the same CO2 level.