Multiplayer doesn´t work.. (Xbox One)

Hey everybody,

Why am I not able to connect to the multiplayer? Untill I have to presws “X” to join the multiplayer everything is fine. Then my Xbox tries to connect, but after 20 seconds it tells me, I cannot be connected and I should check my internet connection. I have Xbox Gold and a 100 Mbit/s internet connection. Moreover my Xbox One is connected via a LAN cable.