Disabling authentication on the master domain controller the slave HC is unable to connect.

A remote CLI however is able to connect so I suspect a failure in the slave HC rather than the master.

The message logged on the slave HC is the generic: -

[Host Controller] 14:39:39,724 ERROR [org.jboss.remoting.remote.connection] (Remoting "localhost.localdomain:MANAGEMENT" read-1) JBREM000200: Remote connection failed: javax.security.sasl.SaslException: Authentication failed: all available authentication mechanisms failed

Enabling TRACE logging reveals the following error: -

17:28:36,803 TRACE [org.jboss.remoting.remote.client] (Remoting "localhost.localdomain:MANAGEMENT" task-2) Client authentication failed: javax.security.sasl.SaslException: Callback handler invocation failed [Caused by java.lang.NullPointerException]