When the device has been disconnected for more than 24 hours, you will see the "disconnected" state in red in the app. The device cannot be controlled, for this reason it is important to proceed with the reconnection.
First of all, check the version of the firmware in the settings:
If none of the solutions provided work, contact support.
Please note: it is also possible to connect the device via hotspot, however, it is best to use a home network, since the phone should always be next to the device. Also, a hotspot connection is not as stable and lasting as that of a fixed router.