Debasish SahooI think i am failing to tell you exactly what's happening with me. My phone's mobile data is turned on but i dont recieve notifications , when i open the app all notifications on the "chats display" section and all calls arrive just like a pop up.
So you are facing this issue on whatsapp only? If yes then go to settings>Apps and notifications>Whatsapp>Notifications and then turn it on, if already turn on then turn it off and turn on.
If the problem still persists then try restart your phone once.
Last option would be reinstall your whatsapp it will definitely help you.