Mi Door and Window Sensor can't connect to Home Hub.

To check whether Mi Door and Window Sensor can't connect to Home Hub, please refer to the following steps:
1. Use the eject pin to poke the reset hole of the Door and Window Sensor. If you hear voice prompts like "Normal link confirmed" from the Hub, it means the sensor is communicating well;
2. If not, move the sensor closer to the Hub and try again. If you still don't hear prompts, the sensor might need re-adding or battery replacement;
3. Move the sensor unit close to the magnet unit and separate them 2 or 3 times;
4. In the Mi Home app, go to the Door and Window Sensor's home page and refresh the device records (log). If you see related logs, it means the device is working correctly;
5. If the issue persists, delete device in the Mi Home app and add again.