Hi, I use Confluence Server on a CentOS 7 machine.
Firewall is OK (8090, 8091, 8000 etc.).
I can't modify any page, it says "Editing is not currently available". Synchrony results up and runnings from General Settings, on port 8091, 1GB Heap.
I must switch to Limited or Off mode in order to edit pages.
I use also Jira Server and Bitbucket Server on the same machines with no problems at all.
DB is PostgreSQL Server 9.2.24.