Up.
The same thing is happening to me again: When I try to login, I get the worlds list, click on Dunarsund, and then get the maintenance page.
I'm using Chrome Version 49.0.2623.87 (64-bit) on linux mint, usually on private mode.
Clearing cache => doesnt' work.
Using private navigation window => doesnt' work.
Using normal navigation window => doesn't work.
Deleting cookies => doesn't work.
Desactivating all extensions => doesn't work.
Using Firefox => doesnt' work.
On mobile it works.
The FR worlds are accessible.