Although I went into detail on this on your closed bug report, I'll say the same here so others who find this issue can figure out the problem.

As I mentioned originally, this is definitely a firewall problem. The clue that makes that clear is the fact that only people on your LAN can't join, but people from the Internet can. Firewalls can be configured to allow/deny traffic on your local network, so that has to be what's happening here. If your firewall says it's not doing that, then you either have another firewall running or you have a bad firewall. The most likely situation is that you have the Windows firewall running in the background. If you have another firewall already, you can just disable the Windows firewall outright.

As for the IP, what you're probably seeing is that Dream Daemon is giving you the external IP address that everyone outside your LAN sees. The IP used inside your LAN is only valid there (it is usually assigned by your router as a way of telling the local connections apart), so local users should be able to connect to either one of those IP addresses. Users joining over the Internet can only see the external address.