I am going to suggest that you go back to the basics. Make sure the content server is running. Then try to access it from another machine on your home network by using the ip address and the port number, for example
http://192.168.0.11:8080. You must, of course, substitute the ip address of the machine running Calibre and the actual port number if you have changed the default. Does this work?
Once we know it is working internally, we can then setup port forwarding. What is the brand and model of your modem/router?