Nintendo has an upcoming maintenance period planned on December 21, likely the last before the big Christmas rush. The maintenance will impact several recent releases, including Super Mario Maker, Xenoblade Chronicles X, and The Legend of Zelda: Tri Force Heroes. Super Mario Maker will be affected by two maintenance periods as well.
Super Mario Maker
From Monday, December 21, 2015 3:00 PM – Monday, December 21, 2015 5:00 PM Pacific Time
and
From Monday, December 21, 2015 8:50 PM – Monday, December 21, 2015 10:00 PM Pacific Time
Xenoblade Chronicles X
From Monday, December 21, 2015 4:30 PM – Monday, December 21, 2015 6:00 PM Pacific Time
The Legend of Zelda: Tri Force Heroes
From Monday, December 21, 2015 9:50 PM – Monday, December 21, 2015 11:00 PM Pacific Time
During the maintenance periods, you’ll be unable to access all network services related to these games.