Players world-wide are reporting that they got locked out for more than 71.5 million minutes from the online multiplayer.
Until now it was reported that if you quit early or if you target a player over others the bug can reproduce. However, only some are affected as most players still get banned for 5 minutes for breaking the rules. Players are advised not to play Smash online or risk being banned. Nintendo was notified about what is happening and they are most likely already working on it.
In case you still want to play the game until the bugs are fixed but don’t want to wait in case you are banned you should follow the next suggested steps:
-play one-on-one in For Glory mode
-In case of four-player modem don’t pick on just one character in the game
-don’t quit during a match (loosing internet connectivity will bring the same results)