http://www.pcgamer.com/fortnite-servers-will-be-unstable-for-the-next-week-because-of-meltdown-patch/

Epic Games' attempt to protect its services against the Meltdown CPU exploit could make it difficult for some players to login to Fortnite for the next week, the developer said yesterday.

Epic is patching its cloud servers—which is "heavily relies on"—to address their vulnerability to Meltdown, and the result is that the game will be unstable over the next week.