Yes, it works now. Thank you. But I think it does not download the books I choose. It says downloading in the background, but I don't see, that books are added to my library.
Oh, and how can I bookmark this connection? right now I always have to type in my ip etc. again. I holded this button and the menu opend, where I said bookmark. I tapped on that, but the calibre Library is not added to the tabs like the Newspapers etc.