I have been running Jira and Confluence on a Mac server for years and they were extremely out of date. I have been using the Jira internal database for authentication.
I recently went through an arduous process of updating to current versions (Jira 7.9.2, Confluence 6.9.0) and all looked good. Then for some unknown reason a user was unable to log into Confluence. I believe this has to do with Application Links and indeed App Links is reporting outgoing and incoming authentication disabled in both Jira and Confluence, but whenI try to make changes I get 'XXXX is not reachable.
In Confluence I have:
Application name: JIRA
Application URL: http://jira.mydomain.com.au:8080
Display URL: http://jira.mydomain.com.au:8080
For Connections:
Outgoing Outh -> jira.mydomain.com.au JIRA Troubleshoot
Incoming Outh -> jira.mydomain.com.au JIRA Troubleshoot
In Jira I have:
Application name: Confluence
Application URL: http://confluence.mydomain.com.au:8090
Display URL: http://confluence.mydomain.com.au:8090
For Connections:
Outgoing Outh -> confluence.mydomain.com.au JIRA Troubleshoot
Incoming Outh -> confluence.mydomain.com.au JIRA Troubleshoot
The domains are correct. Not sure about the application names or where they are set.