Xbox one x downstairs Xbox one upstairs NAT still Strict

Hello,

I cannot for the life of me get this fixed the easiest way possible. I have an Xbox One X downstairs can call it Xbox #1. I have an Xbox One upstairs in my bedroom, which can be called Xbox #2. I have a gateway, that is both router and modem. First question: can't find in the forum if my Gateway allows two different consoles on my network. I've read so many help FAQ's, and I am not good with networks, port forwarding, alternating ports al that stuff. Is there a simple step by step process to have both X box consoles on the network? I'm only playing one of them at a time, and with Xbox #2 I can't get my NAT type to open. Please please can anyone help me figure this out? Much appreciated.

:)