Normally push notifications do arrive quite quickly. The most common reason for notifications being delayed is the device had no internet connection or a poor connection and the notification did not arrive until the connection was made.
However, there are some othe cases where we've seen them get delayed:
Some home and commercial wifi routers will cause the device's connection to Google's FCM/GCM servers to be closed. The device later re-opens the connection and receives the delayed notifications. (Discussed here: https://groups.google.com/forum/#!topic/android-gcm/Y33c9ib54jY)
Some custom versions of the Android OS have a "power-saving" setting that can cause notifications to be delayed or ignored. For instance, Sony Xperia devices have a "Stamina Mode". (Discussed here: https://talk.sonymobile.com/t5/Xperia-Z3-Compact/Notifications-not-Working-When-Phone-in-Sleep-Mode/td-p/879641)
Some Android devices can enter a low power mode when their battery is low that may cause slight delays in receiving notifications. This is more common on Android 9 devices with the New Power Management Restrictions:
- Android docs: https://developer.android.com/topic/performance/power/power-details
- Testing: https://developer.android.com/about/versions/pie/power#testing
As with Android, some wifi routers will cause iOS notification delivery delays.
Notifications may be delayed if "Restrict background data" is checked for the app, if Wifi-Optimization is turned on in the advanced settings, or if priority mode is enabled.
"Low Power Mode" is enabled. If in your Settings > Battery > Low Power Mode is enabled, this will reduce the rate at which notifications can be received or turn them off completely.
WhatsApp has a good list of instructions on troubleshooting delayed Android and iOS notification at the bottom of their FAQ page here: https://www.whatsapp.com/faq/en/android/20887936
As with Android, some home and commercial wifi routers will cause the device's connection to Google's FCM/GCM servers to be closed. The device later re-opens the connection and receives the delayed notifications. (Discussed here: https://groups.google.com/forum/#!topic/android-gcm/Y33c9ib54jY)
Depending on the browser being used, there are a few factors that determine if a notification can be received when the browser is not running.
|Notifications Not Shown|