Not always getting push notifications, Facebook Messenger causes device to crash...

[AC Question]

I have a new Vodafone Smart Prime 7 with Android Marshmallow preinstalled.
Notifications are rather unreliable. Please note, all the usual settings are correct and I have already un-opimised the affected apps from the battery optimisation thing.

With some apps, the notification seems to come through at the right time, but I get no actual alert until I activate the phone. With Whatsapp for example, I won't get any indication of a message until I switch the phone out of sleep mode.

Facebook Messanger is the worst. Whenever I get an incoming message, the phone completely crashes. It removes my wallpaper and the screen keeps fluctuating between off and on; I have to physically restart the phone to get it working again (and even then, I get no actual notification that I've got a new message).

How can I sort this out please? Thanks.

 

[B. Diddy]

Welcome to Android Central! Did you install FB Messenger from the Play Store, or from somewhere else? If it wasn't from the Play Store, there's a chance it isn't compatible with the phone. Look at the FB Messenger app page in the Play Store website on your computer browser, and click Install--does it show your phone as compatible (or already installed)?

Do you have any "RAM booster/cleaner" apps or power-saving apps installed or preinstalled? If so, uninstall or disable them.