I have a 10-ping and 200-300 FPS in Fortnite but I'm still lying. The connection shows 10% packet loss and there are red lines all the time.
If 10% of the packets that you send to the server are lost, 10% of the information is almost like a lay.
Too much fps can also cause problems
It's up to the 10%. Maybe a firewall or something else that filters out the packets.
Open all the ports that Fortnite needs in the router and PC firewall.
By the way, so many FPS bring you nothing. You can activate vSync.