Unable to log in to only one concrete character

[Queensglaive]

Okay, here wasting my time since official and efficient Support doesn't exist, but maybe other users can help.

—I can't log in to my main character on my Data Center.
—I get the "Connection with the server was lost." pop-up with the 90002 error right before spawning.
—I can log in to any other character.
—I can log in to my main in other Data Center (Light), but not in the one it belongs to (Chaos).