Here's the thing, maybe your cable/wireless internet provider are dealing with problems when they send internet to you.
If your connection has any kind of problem, your Wii U won't download the update package properly, and even 1KB loss will show you an Error Code 162-XXXX and its similarities.
Or, maybe your router is with a firewall that gives to Wii U time-out problems, making the update file to get corrupt.
My solution is to hire a 3G/4G internet modem and share the connection securely through your wireless on your laptop. 
That solved my 162-2011 error code on the first try. 
You can lend from a friend just to do that.
By the way, Nintendo already released another update, and with my 3G modem I downloaded quietly and installed successfully.