Actually, it doesn't any more, it was a setting in my router that caused that... my local is now always
http://192.168.1.118:8090 so it is the only "catalog" link I need.
The reason I like to do it this way is that I can "shop" amongst my books (I have been ereading for 4 years now and spent a fortune on books which I "re"read eventually...). You can browse the Calibre Library by Newest, Author, Title, Tags, Series etc. and get the cover and synopsis on your screen as well as the download button.
Great when you have a lot of books and can't be bothered to go upstairs to the computer...