As soon as you are out of the Bluetooth range, the app will no longer be able to receive real-time
temperature readings. Check to see if the Bluetooth LED indicator light on the bottom right of the control is solid blue. If it is blinking, it no longer has a Bluetooth connection.
Bluetooth range can be effected by many factors including interference from other devices, distance, going in/out of buildings and even by the topography of the land. For the best results, make sure you are in direct line of view of the control.