Two possibilities (or maybe three) :
- Too many people, putting the NoE servers on their knees.
- eShop unnanouced maintenance to prepare preload.
(unlikely) - Your provider has a problem.
Thanks for your answer! I find the first two hypotheses highly unlikely: I've been having this problem for about 4 days in a row now, I don't think NOE servers or the Eshop specifically could be down for that long without a lot of people noticing and complaining (including on GAF).
I did change my ISP recently, so maybe it's related to that? However, all my other equipment (PS4, PS3, 360, laptop, tablet, phone) has been completely unaffected by this change, no problems with the connection there..
Not sure what the problem is, but try downloading half of them and then let it install to the Wii U by turning it off for a while. Once it says installed on the download management screen, download the other two and do the same.
Thanks for your help! But you see, my problem is that I don't even get to the point where the download starts. The furthest I've gotten is to the point where I've added all the packs to my Eshop "cart", and then I've pressed "purchase" or "confirm" or "download" or whatever, and then it's been loading for a long time and then I get the error message. But sometimes I get the same error message trying to even load the Eshop.
This is very frustrating. I likely won't get the game until next week at the earliest, but I'd really like to have all the downloads sorted by then since I wanna jump into the game straight away.