I assume you don't have a public ip address on all your computers. You can go to www.ipchicken.com to get your current public ip address.
You didn't state what port you have setup on your server. The default is 80 and the recommend port is 591. If you use port 591 you will have to append it to the end of your public ip address proceeded with a colon to connect to the server. Example 555.555.555.555:591
You will have to setup port forwarding on your router to forward port 80 or port 591 to the local ip address. (Server ip address) Or the port that you using. Then you have to forward port 5003 to your local ip address. You may have to get a copy of your router's manual and see port forwarding.
You will also have to be sure that these ports are open on your firewall.
There are only 6 TCP ports that need to be open for communication between machines:
Added in Server 9?
Apache/IIS Web Server Default HTTP port used for access to Instant and Custom Web Publishing - can be changed by the user configuring their web server and will not affect functionality of FileMaker Server/Advanced other than the port that is needed to access web publishing. If SSL is used, then the default port is 443
This port must be open on the machine that is functioning as the Web Server
Networking Port - used by the WPC and remote copies of FileMaker Pro to connect to the database server
This port must be open on the Master machine in the configuration
What is an IP Address versus a Domain Name Server Entry?
When a user at a remote location opens a webbrowser, that user can enter an IP address or a Domain Name
IP Address - 18.104.22.168:591
Domain Name - MyFMPIWPDB.com
The Domain Name is translated by a DNS server into the IP Address.
Translates into the Static or Dynamic Address 22.214.171.124 Port 591
This is a request for a Filemaker IWP database hosted on the computer at 126.96.36.199
This IP Address may be
Single computer hooked up to a Cable or DSL Modem
OR one of multiple computers that are connected with a router to a Cable or DSL Modem.
The Router has been Instructed to Forward requests for that Port to the correct computer.
http://portforward.com/ (instructions for many different routers to set forwarding requests to the correct computer)
A Dynamic IP Address is the no extra charge Cable or DSL standard.
A Dynamic IP Address may change when the power goes out for some time, and maybe not.
A Dynamic Ip Address is selected from a pool of IP Addresses that your Internet Service Provider pays for.
Your ISP buys and pays for their Static IP Addresses.
They share this pool with their clients in a geographic area or all clients.
Your ISP may change it randomly when you turn off your Cable Modem or DSL Modem/Router for an hour or a day.
Your Dynamic IP Address may stay the same for years, or may change tomorrow.
WiKi about http://en.wikipedia.org/wiki/IP_address
A Static IP Address is yours as long as you pay your ISP $5 once, or $5 a month, depends on their policy.
All main websites have a Static IP Addres, it is a basic web asset to have.
Google probably has thousands if not tens of thousands Static IP Addresses.
INTERNET > sends request for Port 80 (WebServer by default) to your Static IP Address
If your DSL Router/Modem or Cable Modem has ONE computer attached, AND that computer is running a WebServer (Apache for instance) the request is processed by the ONLY computer attached to the Router/Modem and your webpage is returned to the asking computer on the internet.
INTERNET > sends request for Port 591 (Filemaker) to the router / modem.
The router / modem has been instructed to forward these requests to a specific computer at IP Address 10.0.0.23
The computer at that address responds, your remote user sees the IWP login page served by FMP or FMP Server.
A Remote Filemaker Client can be pointed to your IP Address http://188.8.131.52:5003
Your router has had been set to forward the request on Port 5003 to your Filemaker Server Computer.