Check whether the device works locally
A physical button or manufacturer app can reveal whether the problem is device-level.
Check shared infrastructure
If several devices fail together, look for a common router, hub, bridge or cloud dependency.
Separate connection from automation
A reachable device can still have a broken routine.
Change one thing at a time
Multiple resets at once destroy useful clues.
Keep in mind. Compatibility is not permanent. Confirm the current manufacturer, platform and certification information before purchasing, resetting or migrating a device.