Here's Nintendo's page:
http://www.nintendo.com/consumer/wfc/en_na/ds/results.jsp?error_code=1119001&system=Wiiu&locale=en_US&locale=en_US&action2.x=28&action2.y=33
Although you said your Wii U was on the network, maybe try recreating its network connection. I saw some odd behaviour from my Wii U because I'd moved it to a friend's house and set up to connect to his network. When I brought it home, things like eShop were sluggish and strange until I recreated the network connection in system settings.
"The worst part about these reviews is they are [subjective]--and their scores often depend on how drunk you got the media at a Street Fighter event." — Mona Hamilton, Capcom Senior VP of Marketing
*Image indefinitely borrowed from BrainBoxLtd without his consent.
