Apologies in delayed response.
For accessing the server on the internet, you need to have the Public IP open to internet on the NSG for the port number on which the service is running. Ensure there are no NSG rules blocking on the Subnet level for required ports.
Once this is done, you can use this tool and see if the Public IP is open on the required port. If this is open and the service is running you should be able to access.
If you get closed when using the tool, then you can check the local Windows firewall and allow the port on that aswell.
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