You are saying that everybody on your local network (LAN) can connect to your server?
Can you please tell us, how they connect?
Do they enter your computername to connect to or do they enter an address to connect to?
If they enter a computername then you would need to resolve the computername to an IP address.
from a console session, try to enter the following command "ping ". don’t add the ", and replace for your actual computername.
This command does a couple of things, one is, resolve the computername to an actual IP address it is using.
Depending on your OS, version and configuration it could give you are IPv4 address or a IPv6 address.
For now, I will presume it’s an IPV4 address.
Once, you have this IP address, try to connect from minecraft to this specific IP address.
This should work without any problems.
Now that we have the local IP address of your server.
You need to get the port, fortunatly your already have the port number that your minecraft server is running on.
The third step is to get your external or also called WAN IP address.
You can get this IP address easily by going to for example: http://whatismyipaddress.com/
This website will show you your external/WAN IP address. write it down, you will need it in the next step.
Now go open the webinterface of your router, in most cases it would be something like http://192.168.1.1
You can also look at your network address configuration and write down your gateway address, most of the times this is also your router address.
Now that we have all that information, and you are logged on to your routers webinterface, you will need to setup the port forward.
In this part you enter a couple of things.
Protocol: TCP/UDP : select TCP for this specific config.
StartPort:
EndPort:
WANIP: (depending on the router this is not visible or preconfigured)
LANIP:
Now the router knows, that if somebody from the internet is accessing your WAN IP address, that it will have to listen on the startport: , and if it receives requests on that port, it will forward all data to a machine on your LAN using that same port, and therfore an Internet user will be able to access your server.
Now, ask your buddies on the Internet to test your server, let them access your .
Do note, that it some cases your WAN IP might change from time to time. So this could result in you having to modify the Portforward from time to time.
In some routers this issue can be resolved, by making use of dynamic DNS, but that’s a whole other topic 