And apparently all servers will be offline at some time tomorrow, for about 4 hours. Exact time to be determined.
In the early morning of Wednesday, December 8, we will be conducting maintenance across all Worlds to address server errors aside from those mentioned above, as well as a few issues that can be resolved on the server side. This requires all servers to go offline and is estimated to take about four hours to complete. Details on maintenance timing will be announced in the future. I’d like to ask for your understanding and cooperation regarding this matter as well.
Source:
https://na.finalfantasyxiv.com/lodestone/news/detail/4269a50a754b4f83a99b49341324153ef4405c13