Creo ModelCHECK > config_init_options > ASYNC_PORT
  
ASYNC_PORT
<integer>
Specifies the communications port between Creo ModelCHECK and Creo Parametric to allow feature highlighting and updating. This port number can be from 1000 to 70000. The default is 3001.
Creo ModelCHECK opens this port when Creo Parametric is started. This port remains in use for the duration of the session.
If during startup Creo ModelCHECK detects another process using the default port, it increases the port number by 10 and tries again. Creo ModelCHECK repeats this procedure 5 times before displaying an error message and disabling Java.