Check out the patch notes for the v20 Lovely Update here:

[Website] Disconnect using Chrome

MapleStory 2 Rep: 460
Posts: 5
in Bug Reporting
Around 2 seconds after logging in to the Maplestory 2 Website via while using Google Chrome i get an error message that says "You have been disconnected." I obviously get logged out after that. It happened every time i tried it in the last two days (23.11.18, 24.11.18). Posting this using Firefox.