Acronis Cyber Cloud: Cannot connect to Acronis Cloud from CloudBlue integration with "SSL connect error"

Symptoms

• APS package is installed on CentOS 6.x
• When trying to connect to the Acronis Cloud from the APS endpoint, the following errors appear in /var/www/html/backupservice/log/Events

2019/04/30 10:54:17 5cc829584d633 Error Request error: SSL connect error File:'/var/www/html/backupservice/tenantBase.php' Line:'602'