This issue has been identified while validating if the Dispatch Router is reconnecting properly with the Broker in an HA scenario, when Master instance fails over to the Slave and then fails back to the Master.

When the Master is restarted (and the backup server stops its acceptor), the Dispatch Router attempts to reconnect with the master broker as soon as it detects that its acceptor's port is available, and we noticed that the open frame received by the Router (from AMQ), sometimes, does not have the "fail-over-list" present in the properties.

Looking at the timestamps in the router logs, the "open" frame was received before the "replication" completed on the broker side, and that is a possible reason why, sometimes, we do not see the "fail-over-list" on it. If the Router is restarted (after replication is done) then the "fail-over-list" comes back as expected.