What version of FileMaker?
Exactly what is the user doing to attempt a connection and what do they see on the screen when they do?
FM tells the user that the DB or the URL is not available. But even via Browser i can reach the network where the server with FM is running....
But can you reach that specific machine?
I am assuming that you are unsuccessfully attempting access from outside of the server's network.
Is it possible that you don't have a static IP address for the internet router that you access and which then forwards FMP access to a specific machine on its network? If so, the address may have changed on you. You'd also need to check to see if changes were made that mess up the port forwarding that has to take place for this to work.
Well like I said, with my MacBook Pro I can access from office my server, so the connection from office-network to server-network works. It is only the Windows computer who does not find my server-network.
I use a dyndns.org adress.
That PC is on the same internal network?
Check the IP of that PC, if it's a correct IP (same range than Yours), then try a 'ping' from the server (or from Your MacBook) to that PC client. There's a network utility that can ping - or You can open the terminal an do a 'ping 192.168.what.ever'
Any firewall? Any blocked port 5003?
If this were FileMaker 11 or older, I would have suggested this from the start, but since you've ruled out several other possible causes...
For More Information see: FMP installer does not install server.pem file
This is one of many acknowledged bugs that can be found in the Known Bug List thread here in the Report an Issue section of the forum.
It can also be downloaded as a database file from: https://www.dropbox.com/s/jt09b82i0xijbu3/FMP%20Bugs.zip
I solved my problem.
I talked to my ISP and they blocked some ports. So i had to get a static IP and there the ports are open and now it works.
The only strange thing is that even with ports blocked, it always worked perfectly.... strange
Thx for your help