Can you try to add this property to your host-controller startup parameters, like below:
$JBOSS_HOME/bin/domain.sh -Djboss.domain.master.address=xxx.xxx.xxx.xxx --host-config=host-slave.xml -Djboss.host.domain.connection.timeout=60000
If you are starting your JBoss as a service, you will need to add this property to your domain.conf file, like below:
Thanks for your suggestion. Would you mind clarifying your thought behind it?
The log entry I listed is presented 10 times as I would expect based on how the Host Controller attempts to connect to a Domain Controller. Should I expect a different message if the Domain Controller is not responding in a timely manner?
Found the solution in the RedHat JBoss EAP documentation.
The "Promoting a host controller to be the domain controller" section/information isn't presented in the WildFly documentation.
The commands are presented at various locations, but never referenced/used in an example that shows their use for promoting the Host Controller running with the --backup flag.