In Fortnite: Battle Royale is currently experiencing many issues on PC, PS4, Xbox One, Mobile, and the Switch. The servers are having trouble and matchmaking is not working. The new mode Horde Rush has also been disabled.
Update 7:20 PM: The issues should now be resolved. Fortnite tweets that matchmaking should be working again.
Continuing with the original announcement
What is the server status? As soon as the new game mode Horde Rush was on the servers, there were already problems. The mode was first swapped with another LTM and eventually completely disabled.
But that was not the peak of the problems in Fortnite. Because now the servers are still having issues and matchmaking is not working at all anymore.
Currently, Epic reports: A “Partial Outage” in matchmaking. This means there is a partial outage and matchmaking is not functioning.

Horde Rush and matchmaking are offline
Epic has also announced this via Twitter. They are having issues with matchmaking and are working on a solution. They will inform us as soon as possible when there are any updates.
The mode “Horde Rush” has been temporarily replaced by “One Shot Duos” – they are working to bring the mode back to Fortnite.
When will the issues be resolved? Epic will report back as quickly as possible when there is progress. Since currently no one can play Fortnite and millions of players are waiting impatiently, this issue should currently be of the highest priority. We will let you know here as soon as there is any news.