https://www.gamespot.com/articles/fortnite-servers-going-offline-ahead-of-520-update/1100-6460980/

Epic's massively popular battle royale game, Fortnite, is going down for routine maintenance tomorrow morning. As announced on Twitter, the developer will take the game offline early on August 7 as it implements a new update across PS4, Xbox One, PC, Nintendo Switch, and iOS.

The maintenance period is scheduled to begin at 1 AM PT / 4 AM ET / 5 AM BST. As usual, Epic hasn't revealed how long the downtime is expected to last, although it typically doesn't take too long. Maintenance periods for Fortnite routinely run between one to two hours, though that could vary depending on the update.