Android firebase push notifications are not delivered after coming to online from offline when we use rest api php

_x000D_ _x000D_ I have followed the below tutorial for firebase push notification in android using php rest api https://www.simplifiedcoding.net/android-push-notification-tutorial-using-firebase/ I can able to receive push notification only when the registered device is online.. when its offline at time of sending push notification if the registered device is offline and if it comes online later, those notifications are not getting received.. When we send push notification even though device offline firebase response tells that its successfully delivered.. {"multicast_id":8938362209686545843,"success":3,"failure":0,"canonical_ids":0,"results":[{"message_id":"0:1493758633066681%9383da03f9fd7ecd"},{"message_id":"0:1493758633067106%9383da03f9fd7ecd"},{"message_id":"0:1493758633066683%9383da03f9fd7ecd"}]}[] Do I need to do anything more for offline feature other than the above tutorial? Tried adding FirebaseDatabase.getInstance().setPersistenceEnabled(true); in the multidexapplication class, but still not working. Thanks in advance