One of the irritating aspects of the wii-u is that it updates automatically. Here's a tutorial on how to bypass that.
How to Block Automatic Updates on the Wii-U w/ CCProxy
Download ccproxy from its official website.
Open ccproxy and click on options to check the http port being used. You may change the port if you wish, but I left it at 808 to prevent any conflicts.
Close the options menu, and click on account.
In the permit category section, make sure it says...
How to Block Automatic Updates on the Wii-U w/ CCProxy
