Thanks for the reply.
As far as I can see, it usually happens when I'm in more populated areas like in Limsa Lominsa or Gridania. If that happens, I wouldn't be able to login back after as I'll get hit with the same error while loading into the game after character selection.
On some occasions, it even happens in maps with no people around, like in front of the housing apartments. The play times varies, happens during around 7AM GMT+8, happens also during 5PM GMT+8 and beyond. (Tonberry JP server if that helps)

I don't have any other programs running at the same time other than my browser, which i usually close down everything to try login in again once this happens.
I'm using wired connection.