By default, Enterprise Server uses ephemeral ports for its communication listeners, to prevent clashes occurring with other network software on your machine when a listener starts. However, this can make debugging more complex, since Enterprise Server is likely to be assigned a different port each time it starts.
To force Enterprise Server to use a fixed port number for debugging purposes:
The existing setting should be *:*.
The second * indicates use an ephemeral port number.
During the startup sequence, watch for a mention of dynamic debug enabled. If you missed it, check the log by opening Enterprise Server Administration, clicking Edit in the JCLDEMO row, and selecting Server > Control > ES Monitor and Control > Display.