If your synchrony cluster failed to start in AWS, the Collaborative Edit in Confluence will not work. And if your environment meet all the following criteria. Then I think you are in the right place. As I had the same issue, and finally figured it out that Synchrony has seperate JVM settings. The proxy settings for Confluence JVM does not pass to Synchrony. Check this out: https://bitbucket.org/atlassian/atlassian-aws-deployment/issues/44/synchrony-cluster-failed-to-start-with. Technically, it is a Confluence bug.
- Confluence cluster built in AWS
- Confluence managed Synchrony via Synchrony-proxy
- Use AWS role for cluster node discovery
- Need outbound proxy to access Internet