Will not communicate with computer

The instrument starts up with blinking red light then after a minute or so, turns green. In the past I know this means it initialized properly. However, when I start the program, it comes up with "Communication Error. Please check cable or COM: port". switched cables. No help. Not sure how to check COM port on a Windows 11 setup. Any one else had this problem?

Equipment: Perkin Elmer Lambda 365+