For those of you that missed out, in the recent 11.8.0-41 update for the Nintendo 3DS, several changes to how the NIM service handles downloading Nintendo 3DS software from the eShop were made. The main change involves sending an encrypted copy of the user's game ticket to their server for authentication. If the server finds the ticket is invalid, or no ticket is provided, the server could deny you access to the content files you are trying to retrieve.
This level of granular per-title validation will effectively put an end to any software that relies on the open availability of content files on the Nintendo CDN to function, including freeShop, CIAngel, TikDevil, and even PC based clients such as Villain3DS, PlaiCDN, and FunKeyCIA to name a few.
However, up until earlier today, the server wasn't denying anyone downloads at all. However, multiple reputable sources have stated that the changes have begun to roll out and that it is unlikely that any workarounds will be found.
At this time, it seems only first-party Nintendo titles are affected, but it's probable that these changes will begin rolling out to all 3DS titles on the Nintendo CDN over time.