Setting the ip and dns manually solved this error code for me.
http://www.nintendo.com/consumer/sy...=how_to&submenu=wup-online-ht-connect-network
edit: Choose "manually setting ip/dns in the right column.
The best for the wii u is to reserve a static ip in your router, but you you can also use one from the ip-range of your router.
Use the dns server of your internet service provider. If you don't know your dns server, you can also use another one e.g. from google.
The update is very big and the time on the screen is never very accurate.
Starting the wii u the first time is really a pain in the ass.