different things: The first link goes to the webd page, accessing FileMaker-data through the web-interface, the second link is for the database-server-administration, can be restricted. Do You have the access-rights? Is that page available from the WAN?
Are you hosting the FMServer or is this somewhere other than your control? Things to check if you have control:
* check port forwarding (router/firewall) Port forwarding - Wikipedia, the free encyclopedia
* check Domain Name System, if any used locally Domain Name System - Wikipedia, the free encyclopedia
+1 to what Beverly said and also Windows Server will need that port opened up on the firewall for external access.
Port forwarding needs the port "open", yes, any platform.
Ahh sorry Beverly I should stop skim reading , I see you already mentioned the firewall.
The port forwarding needs to be done on the router(s). Port forwarding is already done on your router since port 443 is already working fine for webdirect, so port 16000 needs to be set up the same.
The Firewall needs to be opened wherever a firewall may be and that may be on the router(s) and will also be on the server. The server firewall is accepting local connections to 16000, but I think that by default it will reject external connections to that port and needs an extra rule added.
As for your question for the path that you have said is fine: https://domain-cic.org.uk:16000/
I've just checked an external port checker and it would appear that 16000 is not open - would I need to open this port in the outbound rules?
Copy the same rule that you have for port 443 on your router. It will be pointing to a specific IP address like for example 192.168.x.x
It is an inbound rule, but each router has it's own terminology and interface so I can't really tell you what the router configuration page will say.
Another easy test you can do is go directly to your IP address.
Go to Google and type in what is my ip address to get your IP address.
Then from something external to the network, for example a mobile phone not on the local wifi, navigate to https://ip address:16000
If that works and the domain based webpage doesn't work then there is a problem with domain specific rules