My Wii U is at ver. 2.1.0 U and when I tried to install the 30 meg update, it was unable to install it. It showed the error message that it was unable to install the update and before I could click 'OK' both the Gamepad screen and my TV screen went completely black. I was afraid to do anything for fear of bricking the console, so I left it alone for 2 hours. When I checked on it again, nothing had changed, so I tried to turn off the console using the Gamepad power button first, and when that didn't work, I tried the power button on the console. Still nothing so I finally made the choice to un-plug it.
When I plugged it back in and turned it on, everything was working fine. I went to download management and looked for the update data to delete it but, there was no update data there. I then took a chance on updating the system again and it would check for updates and stay there, FOREVER, if I let it. Now it cannot access any of the services requiring internet access.
Oh, and the connection test shows that it can connect just fine.