Resolution:
The Administrator GUI URL uses port 8080 by default.  If you need to change this port number after installation, you will need to do the following:
1. Stop the Administration Server (Service)
2. Modify the &ltTIBCO_HOME>\administrator\1.0\tomcat\conf\server.xml
<!-- Normal HTTP -->
&ltConnector className="org.apache.tomcat.service.PoolTcpConnector">
&ltParameter name="handler" value="org.apache.tomcat.service.http.HttpConnectionHandler"/>
&ltParameter name="port" value="8080"/>
</Connector>

Change 8080 with another port number of your choice and save the file.
3. Restart the Administration Server (Service)