Xbox: I always fly out of the games and there's: connection broken. Does somebody has any idea?

So for me it is like this: I play on the Xbox one and have all the ports etc set up.

Now everything went for a long time.

But now I always fly out of the games and there's: Connection interrupted. Does somebody has any idea?

Internet connection breaks off. Check router and connection.

What do you think what I did

You do not even want to know what I've thought about the plethora of important information.