Nintendo has scheduled another time for the 3DS’ online features to undergo maintenance on January 9 via their network maintenance page.
Maintenance will begin at 5PM PT, and will run for two hours until 7PM PT. This means it will be in the early hours of January 10 for UK players, where it will run from 1AM to 3AM. During this time, features such as online multiplayer and leaderboards will be disabled across all 3DS games.
This maintenance seems to be nothing out of the norm, with the network having recently undergone maintenance back in December, but it will still disable players from going online in games the may have gotten for Christmas in 2016 like Pokemon Sun and Moon and Metroid Prime: Federation Force.