SkyDock, an adapter worked with sky3DS+(V140), which enable you to get the private header from one of your original 3DS game card, and play online games properly. See more instructions below. News from http://www.sky3dsplus.net/skydock.html
SkyDock Features:
* Build your own private header file for online game play (the original 3DS game card needed);
* Read the original game saved data directly;
* Dump any original game card to .3DS file format;
* Sky3DS+ firmware V140 [05/25/2017]
Change logs:
1. Online games issue fixed.
2. Drive for skyDock's powerful features.
Sky3ds+ firmware v140 and SkyDock released
Re: Sky3ds+ firmware v140 and SkyDock released
Yes, you can even find a total tutorial about this new firmware V140 and Skydock here http://www.3ds-linker.com/content/43-tuto-sky3ds.