Nintendo 3DS/Switch/Wii U - online maintenance planned for April 5/6

Services impacted
Nintendo Switch: online play, leaderboards (unspecified games)
Wii U: online play, leaderboards (unspecified games)
Nintendo 3DS: online play, leaderboards (unspecified games)

Times
Europe: April 6th (3.45AM to 5AM)
UK: April 6th (2.45AM to 4AM)
North America (EST): April 5th (9.45PM to 11PM)
North America (PST): April 5th (6.45PM to 8PM)
Japan: April 6th (10.45AM to 12PM)

from GoNintendo