Test your connection to the Internet
1. From the Nintendo Wii U home screen, select System Settings.
2. Select Internet.
3. Select Connect to the Internet.
4. Select Connections.
5. Select your home network name.
6. Select Connection Test.
7. Select OK
If the connection test fails, you will receive an error code and details on the error. For further assistance in troubleshooting your Internet connection, visit the following page to look up information on the problem - Nintendo Support
If your test completes successfully you can make the connection your default and proceed to the next step.
Restart your network hardware
1. Turn off your Wii U and your Modem/Router and wait for 15 - 30 seconds.
2. Fully power up your Modem/Router (it may take a couple of minutes to re-establish your connection).
3. Turn on your Wii U and test the connection again by following the steps at the beginning of the article.
At this point if you still have trouble then you may have a firewall interfering with your connection. Please configure the following network port within your router from your PC:
Example of port forwarding, this is done from your PC and will differ between devices
Directions for configuring network ports are specific to the hardware being used, and can be found by visiting the manufacturers website.
There are also free resources available such as Port Forward which may help (you can skip the ad to get to the guides). Please note this site is not affiliated with Ubisoft.
if this does not solve your issue, try placing your Wii U in the DMZ of the router or establishing a direct connection to your modem (where available) and retry.
Traffic throttling / Blocked ports
There may also be certain restrictions set by your Internet Service Provider (ISP). If you continue to have trouble, please contact your ISP for details on any specific restrictions on the previously mentioned network ports.
Still having problems?
If you continue to have trouble after completing the above steps, please contact support and include a full description of your problem along with any error messages you may have received.