SEP clients not doing reputation check with ATP on https 443 port.
ATP 2.3.0 doesn't support port 443 for reputation.
ATP 8840/8880/ESX
Till ATP 2.3.0 version we use https on 8443 port.
However, from ATP 3.0 we are planning to support 443 port and Port 80 will not be supported.
Note: Changing to HTTPS in the SEPM is not sufficient, we have to create the certificate in the ATP under "Secure Endpoint Traffic panel". Please check the ATP Admin guide.