This coming Monday, Nintendo will be doing a system-wide server maintenance that is said to affect your WiiU, 3DS and Switch consoles. The announcement came last night saying they would be doing "emergency maintenance" and that online services would be unavailable. It won't affect any of the games you're playing except for ones that are specifically set for online play. It's actually the first of two happening next week, this one starting at 8 p.m. ET (5 p.m. PT), while the second will take place on April 19 for roughly 45 minutes starting at 9:45 p.m. ET (6:45 p.m. PT).