Alright, so now let’s focus a bit on the technology again. For the record, this question is in reference to systems that require access to an external hub or a home network. Due to the fact that the sensor will need to be connected at all times (unless it does not require a hub and therefore could still work without Wi-Fi), there may be times where the connection is lost or times where the connection will not occur.
One of the most common reasons why this can happen is the communication distance was reached and passed. Wireless devices have a limited range and if they are too far apart, they can begin to lag and then subsequently disconnect. But, the issue could be that you did not pair them in the right order (so always reference the included manual).