custo diagnostic server is based on Apache Tomcat. At default custo diagnostic server 5 ist installed in "C:\Program Files\custo diagnostic server".
Open the directory where the custo diagnostic server is installed.
Open the sub-directory "conf".
Open the file "server.xml" with a text editor.
Search in the file for the string <Connector port="
Replace the port with the port number you would like to use. This port us used for http connection. if you use https connections you have to change the value "redirectPort=" also.
Safe the changes.
Restart the Tomcat server.