How automatic Azan actually works

Either the device computes times from coordinates and a method, or it downloads a schedule. On-device calculation keeps working offline; downloaded schedules can go stale.

Solar events are converted to your local clock. This conversion is where daylight-saving errors appear, and it is why an hour-out problem is almost never a calculation problem.

At the scheduled moment the device plays a stored recitation. Anything streaming it from the internet inherits the network's reliability.

Test a full week, restart the device and test again, and re-check after every clock change and firmware update.

The system only needs a location once. A device that phones home continuously is doing more than the job requires.