No agents connected - Private instance on AWS


I have successfully setup the WPT server at

And I have worked with EC2 agents and server can successfully spin up ec2 instances in respective regions. I could see them starting .

However when I go to WebPageTest - Install Check I can see the agents are not connected. This confuses me a little as it was the server which spun up the these Agents but cannot connect to it.
How can I troubleshoot this? Thanks.