Instruct: Classify the given Amazon review into its appropriate rating category
Query: Mixed results - problems with email notifications

I own 4 of these, so I can attest it’s not one faulty unit. In theory the detectors work great when they notify via email, but the trouble is occasionally they go offline without notice and don’t seem to be able to reconnect to our wifi network. Once this happens they can’t communicate via email if there’s a leak, a problem linking to the server or if the battery is low. This communication has happened repeatedly with our devices and in at least two cases the battery died shortly after installation (without providing a low battery notification). This kind of defeats the purpose of owning one of these not so inexpensive devices. As a side note, the firmware has been updated with all 4 units.