On some device, the Power management system or Autostart system will close UnRead service and cause UnRead stop receiving chat messages. This issue may be with the device as follow: Huawei/Honor, OPPO, Vivo or Xiaomi
To fix it:
ASUS
Go to Mobile manager > Permissions (management) > Autostart (manager) > Allow UnRead
Huawei/Honor
Go to Settings (> Advanced Setting)> Battery (Manager) > Find "Power-power-intensive prompt" menu and Allow UnRead
Go to Settings > Apps (& Notification > Apps )> UnRead > Battery > Find "Power-power-intensive prompt" menu and Allow UnRead
OPPO / OnePlus
Go to Settings > Battery > "Energy Saver" or "Power Saver" > UnRead > Find "Background Freeze" menu and turn off
Vivo
Go to Settings > Battery > Find "High background power consumption" menu > Allow UnRead
Go to Settings > Security (& Privacy) > Permissions management > Autostart (manager) > Allow UnRead
Xiaomi / Redmi
Go to Settings > Installed apps > UnRead > Find "Battery Saver" menu > set "No restrictions"
Go to Settings > Security (& Privacy) > Permissions > Find "Autostart" or "Autostart manager" menu > Allow UnRead
Other Android device
Looking for UnRead inside installed apps and fine something like "Run in background" or "Battery optimization" option and allow UnRead
Looking for "Battery" or "Power save" inside Settings and find option to allow UnRead can run in background
Looking for "Security" or "Security & Privacy" inside Settings and > find "Permissions" or "Permissions management" menu > find "Autostart" or "Autostart manager" > Allow UnRead