Here are some tips to keep Biz Daemon running in the background and it can prevent your Xiaomi devices to appear offline.
The steps may vary due to the variety of devices, MIUI versions, or Android OS versions.
1. Keep Biz Daemon running in the background
Go to Settings > Manage apps > Biz Daemon > Permissions > Start in background, tap Accept
If this is not applicable to your Xiaomi device, please skip this setting.
2. Allow Biz Daemon to autostart in your device
Go to Settings > Apps > Manage apps > select Biz Daemon > enable Autostart.
3. Disable Battery Optimization for Biz Daemon
Go to Settings > Apps > Manage apps > select Biz Daemon > Battery Saver > tap on No restriction.
4. Lock Biz Daemon on the recent page
Tap on the Recent button (it looks like the square icon and you can use it to switch between different apps) > long-press Biz Daemon > tap on Lock this app > you will see a Lock icon on Biz Daemon.
5. Keep WLAN or Mobile Data on during hibernation
For WLAN Connection (Wi-Fi):
Go to Settings > WLAN > Advanced setting> allow Always keeping WLAN on during sleep.
NOTE: If this is not applicable on your device, you can skip this setting
For cellular network:
Go to Settings > Battery & performance > tap on the gear icon > select Never on Turn off mobile data when device is locked.
6. Developer options
If Developer options are available on Xiaomi devices, please refers to the following:
Go to Settings > Additional Settings > Developer options > Background process limit > tap Standard limit