After several hours playing around with the configuration on both, Wii U and my modem, and a long chat with a very amateur Nintendo representative I finally managed to get my console online:
This is what I did.
On your Wii U:
1) Go to Internet setting and find your local SSID and try to connect. (don't move anything else yet, just quit when the error appears)
2) Go to MAC address and write it down somewhere. Reset your console.
3) Go to your PC or MAC and open your Motorola settings.
If you don't how just put 192.168.0.1 on the address bar.
By default:
-Username: admin
-Password: motorola
4) Go to Gateway on the left menu.
5) Select the LAN tab.
6) Go to dhcp leases underneath the LAN tab.
7) Go to "Reserve new IP address" and put your Wii U MAC address.
8) You're going to assign an static IP to your console so make sure you assign a free one (if your're not sure you can check below all your devices and see
which IP it's free, for me it was 20, so 192.168.0.20).
9) Check the Bypass Firewall option.
10) In Host Name put Wii U.
11) Now click Add on the button below and it should be added to the bottom list as static inactive.
12) Go to the first option on the same page, GAMING DMZ and if you did it correctly the new added IP address should be available to select as a DMZ host.
Select it and click Apply.
13) Go back to your Wii U and onto internet settings and select the network you register before and go to modify settings:
Security: WEP
IP Address : Don't auto-obtain and put the one you assigned earlier.
DNS: Don't auto obtain and you can use the ones from google
Primary 8.8.8.8. Secondary 8.8.4.4.
Or use the ones assigned to your modem which can be found on your status page of your Motorola settings (I went with this last option)
Proxy setting: Don't use
MTU: Leave it as it is.
14) Now save, test you connection and voila, problem solved.
Hope anyone outhere with the same problem I had, and about to toss their brand new Wii U to the closest GameStop, find this tutorial helpful.
***Edited to remove personal information.***
Message was edited by: NOA_TECH_JOE