Check out the patch notes for the v19 Winter Mischief update here:

Bad lag & constant dcing

MapleStory 2 Rep: 530
Posts: 17
in Tech Support
Past days I and more fellow Maplers prolly experience awful lag issues and constant dc-ing from NA East server . I have been checkign my own internet and it just works as normally should . Guess it is time there is further looked into this because it will annoy many players they constant have to restart the game / or get rollback intot he map to the place where there started when entered the map .