For external access to Jedox (or components) running on EC2 instances, always use the address given in the Public DNS field in the AWS Management Console (including ordering/creating SSL certificates).
Make sure your external users will be able to connect from the outside by allowing inbound connections to specific ports. This can be configured in the Networking & Security area of the AWS Management Console, under Security Groups. First, select the group bound to the EC2 Instance. In the Inbound tab, create new inbound rule for every port that has to be open using a Custom TCP rule.
Note: for Jedox OLAP Server, both HTTP and HTTPS ports must be open. Excel Add-in requires encrypted communication even if the encryption option in OLAP server is set to optional.
In addition, the Firewall must be properly configured on the EC2 instance (same ports are unblocked). For more details on AWS and EC2, see http://aws.amazon.com/what-is-aws/.