If you have a router that doesn't support UPnP you might have NAT problems. Looks like you have two of every other console, so if you haven't had problems with those you should be fine.
We just bought a house with so we have a new modem and we are having some NAT issues but I think we got it figured out.
If you're having problems with that, I can help. I've been helping many people for years on the 360 boards (this account and my fustmonkey account). The multiple xbox or multiple console setup is my favorite!
Like crynryan alluded to, the router is key, not only supporting UPNP but some routers work better with multiiple xboxes than others. The other key thing is that the modem is just a modem, and not a modem/router gateway. If it's a gateway, I would send it back to the cable company (assuming that's what you have) and buy your own modem, make sure it's just a plain modem (that supports docsis 3 if you have cable) and use your own router.