After the server maintenance, everything’s been going wrong. I keep getting disconnected and losing a lot of points. It’s getting worse every day—too many disconnections. 
Mario Kart 8, like all games on Wii U and 3DS, are peer-to-peer.
Disconnections and all that, unfortunately, come with peer-to-peer.
Do you get any error codes with these disconnections?
@CodyMan2000 Is this still an issue?