Console gaming solution to my Apple router network? Using default host/new router?

Hi everyone,

In my house our family has a bunch of gaming consoles, I'm talking like 3 xbox 360s, 2 xbox ones, a few ps3s and ps4s. The reason for this is we have a few TVs, and we like to just pick a TV to play whatever console without having to move anything around etc. It's more complicated than that (sharing, couch size/etc) but that isn't relevant.

My network right now consists of Comcast modem (straight modem, no router) to my Apple Time capsule, that is connected to an express and extreme via ethernet to expand our network to connect devices via ethernet and increase WiFi coverage.

The Xboxes and playstations are finicky with the Apple routers. It's very weird, some games work better than others (Open NAT, Strict NAT, etc. all that nonsense). Apple routers are also not the easiest/best to set up Port forwarding, etc. I have found it cumbersome, long, and generally just doesn't work that well. I haven't played around with it as much as I should, but it seemed like I could only open ports for one IP address (which is problem some because multiple xbox/playstation need same ports forwarded but have different IPs).

So, I played with some more settings (Block incoming IPv6 connections is on, Allow teredo tunnels is on), and it seems all the consoles are working/connecting great, with no errors that we were having before. (For instance, in Dark Souls II it would try to connect to other peer's games but would time out, even though I could see them, on the xbox 360 it worked fine, but xbox one it didn't work)

With these new settings, it seems like my internet is slower. I'm not imaging things, getting to web pages, loading things, etc, is just slower. I've had the same network setup for over a year and it has never acted this way.

What I want to do is this (if there are other suggestions about opening ports, etc. etc. thank you but I just really want a simple solution where I don't have to deal with anything)... buy a new router (non apple) that is very customizable, probably something that can run DD-WRT, Tomato, etc. I would like to connect it to my main router (Time capsule) and assign the new router as the "default host", which from my understanding is like a DMZ and has free access to everything. From there, I would create a new wireless network and have only my gaming consoles connect to it, everything else would stay on the network as is. I would have the new router open/DMZ'ed/whatever you want to call it, allowing free access to any incoming and out coming traffic.

Is this feasible? Would it work? Does anyone see any problems with my solution?

Thanks in advance, I know this is a crazy long post.