Not 100% sure; could it be that the 9.6.1 HF4 installation used TLS 1.1 and the 10.2 installation uses TLS 1.2? While the web server uses TLS 1.1? At least that would be an explanation.
Or that the TLS ciphers used by the 10.2 installation are incompatible with the web server.
Can you test the connectivity from outside via curl and confirm if that works successfully?