Thanks a lot.
But, there is not just a problem with Jetpack. I also tried to use Smush to optimize the pictures and after I did it, the problems arrived once again. I deactivated it, and now everything works again.
I tried “WP Fastest Cache” but got an Error 505 and couldn’t visit the homepage at all as a guest. I tried “WP Super Cache” but got errors that cache isnt working.
