It sounds that there were any changes within the environment (OS / QV release, configurations, move to another server, ...) and it will depend on them as well as how it was performed what now disturbed the communication between the services.
To find the causes and to fix them could be very difficult and therefore it's often much easier to revers the changes and starting at the beginning again by following the official recommendations very carefully. I hope there were current backups of all data + configurations as well as images from the system.
