Currently, this software is not configured to be easily installed on a local machine. There are a few places where the forum location must be given. One of them is for themes. If this location is in the form of 'localhost', ONLY the installed computer can access the themes. If this location is in the form of '192.168.0.2', ONLY the LAN can access this theme. If the location is an Internet IP Address and the router/modem/etc. does not support loopback, the LAN and local computer on which the software is installed cannot access this theme, but everyone on the internet can.
There is another location besides one for themes where the setup asks for a location of the board. If this is set to a local IP, Internet users cannot sign up. If it is set to the Internet IP, local users cannot log in. This has the affect of requiring that you use an anonymous surfing redirector to be able to log in to and administer the account locally.
It would be really nice if the software were changed to allow relative, rather than absolute locations in the settings. This would instantly solve the problem with no setup difference whether you installed it locally or on a distant server.
Full URLs are used so people can do fancy stuff like offloading static content onto a separate server. The easy way to fix the issue is to use a public domain name that associates with the public IP, and add the entry to your local hosts file with the internal IP.
Also, as part of best practices, you really shouldn't be using a server as your local workstation.