Hmm, ok, can you log into the modem, navigate to the STATUS.... CAPABILITY page and see if UPNP is checked (enabled).
@trobichaud2000 do you own a router now? And, if so, are you using it at the present time? If you are, can you describe your network so we have a better idea of how its configured. I wouldn't go out buying anything at this stage. As @VivienM indicated, lets sort out the internet plan first, and have a look at your current network, and then go from there.
Fwiw, I haven't compared the XBox and PS3/4 ports yet, but just off the top of my head, I don't know how any router would handle situations where the same ports were required for two Local Area IP addresses, ie: two consoles running simultaneously. That's actually a very good question.
I suspect that the problem with the PS4 running a restricted NAT might be because the CG2 doesn't have enough space for the number of port forwarding rules that the PS4 requires. And, moving up might not solve that either as it appears that the CN3ACSMR doesn't forward port 80, which is on the PS4s list.
Here is some food for thought. I know from other posts that the CGN3ACSMR will allocate two IP addresses when its running in Bridge mode, that is to say running as a modem only. Typically people only ever plug one router into the modem in that case. You could in theory plug two routers into the modem and end up with two completely independent networks, one for the PS4 and one for the XBox. The drawback, it takes two routers, so, double the cost. This should also work for the CGN3 I believe. So, you might be able to keep your current internet plan and obtain a CGN3 modem. I don't know how much of a cost that would be, but it can't be very much. As @VivienM indicated, it might be cheaper to go to one of the newer plans which has a modem cost built in. But, you have to be very careful doing that as it will breakup any existing bundle you might have running. So that's something that would bear close scrutiny, to determine what the new costs might be.
Looks like @lethalsniper has this cased. A good third party router should solve the problem and allow you to maintain your current internet plan and modem. With that on hand, its a matter of working out the mechanics, UPNP only, Static ports with UPNP, Static ports with port triggering? That might take a little experimentation. A good router might just handle the situation out of the box, without any playing around with it. If you run a search for router multiple console support you will come across a few threads. Here are some of them:
https://www.reddit.com/r/xboxone/comments/1u03ew/list_of_routers_supporting_2_xb1s_with_open_nat/
https://www.reddit.com/r/xboxone/comments/2wjy8z/how_to_use_multiple_xbox_one_consoles_in_a_network/
https://www.reddit.com/r/xboxone/comments/2rznyo/router_recommendations_for_multiple_consoles/
From the first link come this list, which appears to be incomplete, based on the various posts around the net.
Asus RT-N56U
D-Link DGL-4100
Netgear DG834g v5
Netgear R6300
Netgear Nighthawk R7000
Asus RT-AC68U
it looks like Asus and Netgear routers should handle this without difficulty. As @lethalsniper also indicated, the TP-Link Archer C7 will work. It just happens that the C7 is on sale at tigerdirect.ca and canadacomputers.ca for $100 which isn't a bad price for a capable router.
I've also seen references to loading DD-WRT for firmware in place of the manufacturers firmware, and that apparently works as well.
So, this isn't looking so bad after all. Just have to do a little searching around the net.
