Final Fantasy Crystal Chronicles: Remastered Edition makes it difficult for everyone to play online no matter where they live, but the situation appears to be much worse for those in Australian and New Zealand.
For whatever reason, Australian and New Zealanders are unable to get into online games for Final Fantasy Crystal Chronicles: Remastered Edition. If they can manage to hop in on a game, it disconnects just a few seconds later. This isn't an issue specific to the Switch, either. It seems to be impacting all versions of the game.
Square-Enix is yet to comment on the matter, but hopefully they can issue a fix soon.