xBox One & NAT settings?

guitarcookie1

Some help from the technologically enlightened please:

My son is banging on about the NAT settings on our router (BT Infinity Homehub 5) interfering with him playing FIFA & CoD multiplayer games. Aparently he needs them set to 'open' but ours are set to 'strict' (no idea why, never set them)?

I have no real idea of what he's talking about. I've done a bit of googling and it appears that you have to do something in the router settings, but there it loses me completely.

Can anyone help please? I don't want to do anything that'll bugger up anything for the iPads, laptops, 360, etc that all seem to connect with no problems at all...