Setting up Port Forwarding from a router to the machine hosting FileMaker.
Routers are your link to the internet. In order for FileMaker to be made available outside of your network, it is necessary to open a port and direct that port to the appropriate server computer. Your router may look different than this, but the principles are the same. You are looking for the something called 'Port Forwarding'. This is sometimes called 'Applications and Gaming'.
Here is an example of configuring a D-Link router. Your router brand may be different, but the settings are usually quite similar.
Bring up a web browser
enter 192.168.0.1 or try 192.168.1.1
user: admin
password: ********
You will usually find Port Forwarding in the Advanced Tab.
Setup an entry for both FileMaker and Remote Access
FileMaker needs Port 5003, using Both (UDP and TCP)
Set the IP address to the one from the FileMaker Server machine. You may want to set this to a manual IP outside of the regular range of dynamically assigned ports, for example: 192.168.0.25
Remote Access (VNC) needs Port 5900 open and pointed to the FileMaker Server machine's address.
Save Settings
Under the Tools menu, you can change the main password for the Router. Remember to Save Settings.