Why can't I get push notifications on 4g network?

[Luc016]

Hello guys,
I get all my notifications fine when I am on wifi, but when I am on a 4g network I can not get all Push Notifications, from example from Gmail.
I have a Zenfone 3 Running Android 8.0.0
Is there something I can do about it?
Thanks in advance
~Luc