PCWzrd13 says most likely my issue is with using a gateway and trying to DMZ on that same combo router/modem. He (I'll assume PCWzrd13 is a he until I hear otherwise) said the best solution is a separate Modem and router. You can et any kind of router, but the modem must work with your ISP.
Hidden is the runaround I made to get to asking you guys:
The I asked if a gateway can be put in pure modem mode. And best buy said talk to your ISP. Then I talked to ISP tech, and asked if a gateway can be switched into Modem Mode, and they said, in theory you can add extra routers to your network and in theory have 2 sources of wifi. So I can have an N that runs through the house, and a G which is closer to my bedroom for 3DS online moments, because the 3DS only runs on G.
I also have a Dynex 5 port ethernet hub. I don't know if ethernet hub is another world for Wired Router. I suspect it might be because you have to power it on to work.
Another piece of equipment I have is a Gamestop Ethernet/Component Video switcher. There's no electronics, no electricity needed, just press a button and it cuts one off and puts another on.
I suspect the Gamestop one is a Ethernet Switch and not a router, but the Dynex, if I understand it, is a wired router. If that's the case, and what my iSP said is true, then I can put my Dynex behind the gateway, and DMZ the Dynex for the DreamPi, while I put a new router upstairs where my Dynex was, wire in ethernet, and turn on a second G Radio closer to my bed.
Most people don't recommend the router behind a gateway setup. If what I suspect is right, the reason why you don't suggest doing that is irrelevant to me.
Most time when you DMZ something, the other parts of the network are secure. And if you have a PC in the house, you must secure your PC. Unfortunately for multi-console gamers, only one thing can be DMZed.
But all my internet equipment are Game consoles, my Dreeampi, 2 Macs, Dish network, and a networked 4K/3D Blu Ray Player. That's nothing that requires security. If you define the "front" as the closest to the internet source (in my case the main DSL connection) then if the front router has no DMZ, (or I could DMZ it to the back router, I don't know which) and then DMZ my back router to the DreamPi, since the whole path is DMZed, and there's no security elsewhere, none of my traffic is restricted, and the DMZ requirement for the DreamPI MIGHT be fulfilled, it might work. I don't know i the major reason for multi-router fails is security, but if it is, it might work.
Also one other thing, if you own one or more PCs, maybe a "localized firewall" behind the main source and in front of the PC might work. That way you can protect your PC while leaving the rest of your network open for gaming. If that works, that would be the only way I'd consider using Boot Camp to get Windows on a Mac.