Samsung Galaxy s7 not displaying notifications - please help!?

Hi,

So I recently upgraded from an iPhone 5S to a Galaxy s7 and have just set it up. It does not have a SIM yet as I have not switched it from the old phone, all I've done is download and log into all my social media on the new phone.

The issue I'm having is that the Galaxy s7 seems to not be giving me notifications - for example, when I get a Facebook or email notification, it pops up on the iPhone, but not the Galaxy - I have to manually go in and check the notification.

I've checked all the notification settings both overall and in the apps individually, but everything seems to be fine.

When I got a facebook notification earlier on the iPhone, I disconnected and reconnected the wifi on the Galaxy, and then that Facebook notification immediately came through.

Any ideas on what the problem may be?

I considered it possibly being that Facebook and emails are logged into two phones at once, but surely that wouldn't matter?

Cheers