If your Sensor loses connection with the Hub, you should see an in-app message stating that the device has lost connection. You will likely also see the room's temperature reading show up as "N/A". When the connection is restored, you should see the current room temperature showing again.
To help reconnect your sensor, there are a few steps to try:
If after 30 minutes you are still having trouble:
Perform a soft reset on the hub by pressing the soft reset button on the back of the hub, next to the power cord
Once the hub has completed booting back up to a solid blue light, wait about another 30minutes to verify if the in app alert has clearedAt this time, you should also try closing and reopening your app to verify that your in-app messages have cleared.
As a final resort you can reset the sensor by pushing the reset tool, (located on the bottom of the hub) into the hole on the side of the sensor. You should feel the button engage, then immediately release it, and after a few seconds the light at the bottom of the sensor should blink blue.
Once you have reset the sensor, you will need to delete the room, reset the vent(s) for this room, and reconnect each of the devices
Go into the main menu and select System Settings, then select the option to add a room and follow the on screen prompts.
If there are multiple vents in this room, reset the first vent and then add it back in before resetting the next vent in the room.