Hi @SnipEX ,
I did some research and it seems to be a fairly common error. I’m sharing a few posts where different possible solutions are mentioned that might help you.
https://www.epicgames.com/help/en-US/fortnite-battle-royale-c-202300000001636/technical-support-c-202300000001719/why-am-i-getting-matchmaking-error-1-2-or-3-in-fortnite-a202300000014559
Usually, the solution that tends to work most often is running UEFN as an administrator.
If none of those options work, I recommend opening a ticket on the official Epic support website. They should be able to review your case in more detail and provide a more specific solution.
https://www.epicgames.com/help/en-US/fortnite-battle-royale-c-202300000001636
Hope it helps!