Following reports on Nintendo's digital storefront being unavailable for some users and the delay of Pokemon Bank, the company posted the following update on their official Facebook page:
We sincerely apologize for the connection problems in the Nintendo eShop. We understand this is taking longer than expected, but we can assure you that providing a solution is our top priority. We are determined to make sure everyone can enjoy all that Wii U and Nintendo 3DS have to offer. In an effort to manage the high volume of traffic and ultimately improve your experience, we are temporarily taking the Nintendo eShop services offline between the hours of 4 p.m. - 4 a.m. ET. Thank you so much for your continued patience. We will keep you updated.
The issues are mostly likely related to the significant influx of new 3DS and Wii U owners following the holiday. Nintendo in an earlier statement wrote, "Due to the high traffic, players are having trouble setting up Nintendo Network IDs and downloading content in the Nintendo eShop on both Wii U and Nintendo 3DS."
Nintendo also recently announced that the eShop accounts for Wii U and 3DS can be connected by creating and linking the system network ID.