Sometimes I'll lose connection despite having an excellent one. Disconnections are rare enough where it does not bug me much, but they happen more on ranked battles than turf wars, which is really unfortunate. I'm not sure if it's on our end, or if the servers on Nintendo's end have issues.
However, other players disconnecting is such a big problem. Maybe it's either circumstance, or my imagination, but disconnections are far more common than they used to be. It really hurts the overall experience of the game.