Not receiving WhatsApp messages unless I open the app when on 3G (on WiFi there is no delay) I have recently bought a Samsung Galaxy S4, Android version 4.4.2, and for some reason I only receive my WhatsApp messages when I open the app. This only happens when I am on 3G. When connected to a WiFi network, there is no delay at all.

I have uninstalled and re-installed, I have checked the restricted data setting (it is not ticked).

What did I miss?
Samsung phones have an option to sync data in the background, disabling it, saves data, as updates are only checked for when an app is open (email/im/whatsapp etc). You need to enable that (see green icon in image below) to let your apps periodically check for data.


Screenshot (click for larger variant)