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

Servers for Epic's massively popular battle royale game, Fortnite, have gone down for routine maintenance. As announced on Twitter, the developer has take the game offline early on August 7 while it implements a new update across PS4, Xbox One, PC, Nintendo Switch, and iOS. You can read the full Fortnite update 5.20 patch notes to see exactly what's changing in the game.

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.