Re: Xbox 1 Strict NAT problem

 I don't have any PS4s so I can't really give you a definitive answer. My best guess is that this is probably configurable, but which port to block is only a guess. If I had to guess I would choose one of the UDP ports. As for general configuration, yes, you would create rules for the four devices. 

As a side note, you can change the subnet (CIDR) to only block a port for one host. For example you could block access to external port 3478 for just one ip (192.168.1.20/32). This may take you some time to test different scenarios, but I think it's probably possible.

Best of luck and post back if and when you figure it out!