All TCP communications rely on a port to transfer data. Some ports are defined by their protocol (http:80, https:443, ftp:21, telnet:23 etc…). To use the communication handle you must specify a port or else the handle will not know which port it needs to connect to. if a random port is selected like 88, that particular port may not be opened on the device.
I would suggest you contact technical support for the device to see which one is used. i am unaware of any “secret” port number, but if there is one I’d like to know!
If tech support will not help you, the another option is to use a program such as wireshark to ‘sniff’ the communications and retrieve the port number from there.
I hope this helps