A user was running a CentOS Linux 7.3 server with PHP 5.6 was attempting to connect to the WebNative server over port 443 but generated errors such as "fsockopen(): Failed to enable crypto in /usr/etc/portal/PORTAL/libs/SECURITY.obj.php".
This is due to a combination of the CERT and PHP 5.6 crypto modules not supporting some old ciphers like DHE and RC4. Given the version this error was encountered in, the recommendation would be to use a more recent Portal and Server implementation. You can download the recent installers by following the installation KB.
If you do not have the capacity to upgrade, the possible root causes for this issue point towards the certificate on the site is not compatible with the Crypto methods used on PHP 5.6 (fsockopen), you may have to look into the compatibility of your SSL certificate.
You can also take a look at the Configure Apache Web Server with SSL/HTTPS (for Linux) article to verify that you've set up SSL/HTTPS on Linux correctly.