Open a Command Prompt window and execute the following command to confirm whether or not your web application is listening on all IP addresses:
netstat -a -o
You'll see output similar to the following:
Proto Local Address Foreign Address State PID
TCP 0.0.0.0:135 JHUEBEL-VM:0 LISTENING 944
TCP 192.168.0.173:5040 JHUEBEL-VM:0 LISTENING 5096
I've trimmed the output above down to a couple of examples.
Note how the first line has the IP address "0.0.0.0". This indicates that the service using port 135 (":135") is listening on all IP addresses. That would include localhost (127.0.0.1), as well as the LAN IP address (192.168.0.173).
But if you look at the second line, the service using port 5040 is only listening to the LAN IP address (192.168.0.173). So, I wouldn't be able to access that service via localhost.
So, what you're looking for is a line that starts something like this:
If you see "127.0.0.1" (or really any IP address starting with "127."), then the web application you're trying to access is only listening to localhost and is not accessible by computers on your LAN.
So, how do you fix this? That really depends on the application. It will probably require editing a config file. Without knowing the application you're using I really can't help there. Please update the OP with more information about the application and I'll try to help further.