Connecting your Nighthawk XR500 to your Altice One - Gateway?

Can somebody please suggest the best way to to connect your Nighthawk XR500 to your Altice One - Gateway Modem/Router combo? I'm second guessing myself and I'm afraid that my house will get knocked off the network if I attempt to connect it as I have 36+ devices connected at the moment. I'm definitley a beginner when it comes down to networks but my intention is to have the PS5 ready for when I get it since I got the degital version and it will depend on the wifi a lot more than with the PS4. Hahaha....so any advice would be greatly appreciated.

Thanks in advance!