Thanks also another question, does port forwarding nintendo's game ports help at all?Could be that there was a problem on your end or the other players' end or the Mario Kart server. Nothing you can do about it most likely, so your best bet is to just try a new match. If the problems keep coming up, check your connection to see it's good. If you're on Wi-Fi then make sure it's not crowded, as other devices connected to the same Wi-Fi can affect your Wii U. If you're using a Wii LAN Adapter, then the problem likely isn't your fault.
That's the thing with online play... It either works, or it doesn't. Hope this helps!
Annoyingly, I can't do the range but I can do every single TPU port and I could I have and explanation on what port mapping and UPnP are? Also DMZ doesn't help anyways as my consoles been there for the whole time.Well, just to be 100% sure it's not your connection, here are the troubleshooting steps from Nintendo: http://en-americas-support.nintendo.com/app/answers/detail/a_id/13216/p/431
The instructions are bad, though. If you don't have port mapping and UPnP enabled, they suggest you put your Wii U in DMZ (never a good idea) and then on the last page some information on port forwarding, but Nintendo suggests forwarding the entire range of ports from 1 through 65535...
