How to keep the Xiaomi Watch S4 connected to the Mi Fitness APP?

To keep the Xiaomi Watch S4 connected to the Mi Fitness APP, please refer to the following details:
1. Please keep the Mi Fitness APP in the APP whitelist in the APP settings on your phone;
2. Please keep the Mi Fitness APP running in the background without disabling the Bluetooth;
2. Please keep the watch and the phone connected in the available distance;
3. The setting methods are different for different phones. Please go to the [Mi Fitness] APP >> [Device] >> allow this APP to run in the background and follow the respective instruction to finish the settings.