If users can access a service on the local network but not over the Internet, try these solutions.
If you have an Internet router, you may need to configure port forwarding (also known as port mapping) on it.
For more information, see Router port mapping.
If your server is managing an AirPort device, select it in the Server app sidebar and make sure the desired service is listed under Public Services.
For more information, see Manage AirPort port mapping and Wi-Fi login.
Make sure your server’s Internet host name is registered on the Internet, and check the DNS server configuration on the user’s computer.
For more information, see Register the server’s Internet host name, and search Mac Help for “Test your DNS server.”