I have installed Filemaker Server on a Mac mini with OS X server Yosemite.

The Filemaker web service uses a private IP with port 80.

I have disabled the OS X web service so as to not conflict with port 80.

 

I have forwarded the ports 80, 5003 to the private ip on Cisco router epc3928.

 

I can access the FM database from inside the network using

http://<private ip>/fmi/webd

 

I cannot access the database from outside my network using

http://public ip/fmi/webd

 

I think the NAT on the router is blocking access but have no idea how to get around this.

Do you have a static IP address?

What is your public IP address? Some providers use private IP ranges to connect customers most often something in the 10.x.x.x range. Smaller ISP's might use 192..168.x.x or 172.1x.x.x. If you have an IP in one of those ranges as your public IP, then you'll have to talk to your ISP to get access to your FM DB as they do NATting as well. You can easily determine this yourself by going to a website such as whatismyip.com. If the IP addres the website shows you is different than what your external IP is, then your ISP is NATting as well.