Nintendo has been a lot of work on its servers lately, and there’s even more maintenance to come. It’s anyone’s guess as to why so much work is going on (red; you already know the reason why, there’s no need to say it).
The company has posted a notice of the following maintenance schedule, which is set for the end of this month and the first week of October:
As you can see by that schedule above, the maintenance will affect all of Nintendo’s online services across both Wii U and 3DS. That means you won’t be able to access the Nintendo eShop, the Nintendo Network or Miiverse during the maintenance period. This maintenance will also specifically affect Minecraft: Wii U Edition. Take these dates and times in mind so you’re not surprised when you can’t access these services.