The problem in this case is that jboss binds to your external ip.
Most ip adresses are used for ordinary internet traffic, but a couple of them are reserved for internal networks and stuff.
What you want to do, is to get jboss to bind to the ip 127.0.0.1 (also known as localhost, or the loopback interface). That ip always points to your own computer and you don't need to be on the internet to connect to it.
When you have managed to get jboss to bind tot hat ip, you can simply point your browser to 127.0.0.1 and be happy.
I think, in some cases, TCP/IP is only started, if you start the Internet, therefore your experience is o.k.