Please kindly follow the following steps to troubleshoot.

1. Make sure the following settings have been turned on.

a). The device alert at the Details screen – for example, make sure you have chosen "Door is opened or closed" for the alerts of your door sensors, and the alarm strategy area is not set to Disabled.
b). The account setting at advanced settings, for app push notifications, please turn on the Receive Push Message from YoLink App->Menu(three-line in upper left)->Settings->Account->Advanced Settings.
c).  Make sure you have enabled the device alarm and set the app notification to admin at the Alarm Strategy from YoLink App->Menu->Settings->Alarm Strategies->The strategy related to the device. If you are a member of the Home group, and you want to receive app notifications, the host of the home should set the permission in Settings-> Alarm Strategy of device, choose "All" for "Send App Notification"

2. Go to YoLink App->Device screen->Question icon in upper right->Diagnosis of Device Alarm, start diagnosis. If all diagnosis steps are successful and received a 6-digit test message, please proceed to step 3; if all diagnosis steps are successful but you did not receive a 6-digit test message, please proceed to step 4; otherwise, please follow the NOTE information to fix the issue or contact our customer support.

3. In this situation, if you can receive the App Push only when you using the YoLink app, please add YoLink App to the background application whitelist and add YoLink App to battery optimization application whitelist. This setting item is generally in the phone Settings->Applications->Self-starting Applications, or phone Settings->Power->App Restrictions.

4. Please go to this link to make a diagnosis from Google Firebase:
https://firebase.google.com/support/troubleshooter/fcm/delivery/diagnose/android

If the issue comes from Google Service, please follow the links to fix the Google service offline issue; if not, please proceed to step 2 again.

https://support.google.com/googleplay/answer/9037938?hl=en

https://techdevised.com/google-play-services-keeps-stopping/