Hmmm, I am a little out of my depth here. Hopefully someone who knows more about the network requirement for this to work will step in.
If you had Port forwarding done on the router for MC22, you should leave it there. It is actually required for the Client PC to find the Server PC. My comment previously was that you don't need port forwarding on the Server PC, because it can't be done there, and must be done on the router. Bad wording on my part.
Media Center 24 is being allowed through the firewall for both public and private networks. There are are two entries for MC24 in Windows Defender Firewall allowing incoming traffic on any port. Do I need to do anything else to allow inbound UDP packets on port 1900 for DLNA discovery?
I don't believe I have an unusual set up. I have a server running Windows 10 and MC24 Media Center and Server. The BRIX and Laptop are connected to the server library using the access key. I assume this is just a DLNA environment.
I have tried to show dynamic zones on the server but it can only see the local zone. I haven't deleted any zones - they showed in MC22 but not in MC24.
What I can say is that while I am using Norton Internet Security rather than Defender, I have three JRiver programs Allowed through my firewalls; JRWeb.exe, JRWorker.exe, and "Media Center 24.exe". You could try adding the missing one in your environments; Server and Clients.
The reason I'm out of my depth is that I have never received a definitive answer as to how much JRiver Media Network uses DLNA functionality when it is using a Client/Server connection instead of using DLNA Server/Renderers/Controllers. I believe that MC Media Network uses Simple Service Discovery Protocol (SSDP) to find resources such as MC Clients and Servers, but it doesn't use DLNA to connect. You see, DLNA only works over a LAN, and not over a WAN (internet). So the connection you are using, via the Access Key, can't be a DLNA connection. It must be using the specific JRiver Media Network functionality to connect and manage the connections, once SSDP has been used to discover the components. Hence my question regarding whether you were using a VPN.
Anyway, if what you want to do is use JRemote to play music from the Server in the UK to the Client in Singapore, have you tried connecting JRemote to the Client PC instead of the Server (using the Client's Access Key), while the Client is connected to the Server, and then just direct output to the Client Zone? As you say both your laptop and BRIX can see all three zones (server, laptop and BRIX), then JRemote should be able to connect to the Laptop (because it is running Media Network) using the laptop Access Key, and direct output to the laptop...
...I think.
Maybe that comes back to the question of what you are trying to do with JRemote.
