Android 8 delayed notifications Every once in a while my device get "stuck" - I send an SMS or Email, and they are received only after 10 minutes or later. The device can be "stuck" even when the phone is on, and running other apps.

I tried installing Push Notification Fixer apps, but they do not help.

When I send the test and the phone is not "stuck", I get a notification after about 10 seconds.

However, I do receive notifications for Google Voice and WhatsApp when phone is in "stuck" phase, so it does seem app specific issue. Also I have noticed that these 2 apps have permission receive data from Internet , which the Gmail app does not. Seems to be related to what type of push notification is used. see documentation.

Also I noticed the Google Play Store is unable to install/uninstall apps in this "stuck" phase.
Here's a list of things you can try:


Make sure you haven't disabled the app by force quitting on it
Make sure power saving mode isn't on 
Check Data usage to see if Background Data is enabled for the App
Turn off battery optimization from Battery Usage option for the App
Make sure that there isn't any third party overlayer that you've utilized which is utilizing the app sync permissions ( certain launchers/ addons may do so)
Clear cache for that particular App 
Factory reset the Google app by selecting the Uninstall updates option
Install this app and set your heartbeat rate to 5 minutes. It's a quick fix for the issue. It's most probably a network driver issue which the company needs to patch up and in the meantime, you can use this app to ensure normal functionality