Our client is getting below error when they try to call the web service via HTTPS request.

'There was no endpoint listening at <https://XXXXXX/XXXX.svc> - The remote server returned an error: (403) Forbidden.'

But the interesting part is, client successfully connects using the port which was used by the previous version. But new ports are not working. which means still client can call the new service using the old port. But once we change the bindings to the new https port, client is getting above error.

Below checks have been completed already. 

1) Client can successfully access the URL from their server.
2) No firewall rules placed for the newly created port.
2) SSL root certificates are placed in the Trusted Root Certification folder.

Please let me know if you have any idea regarding this issue?

Thank you