TCP and UDP Socket port numbers are based on the "Base Socket" number, so, in order to change TCP and/or UDP Socket port numbers, the Base Socket number must be changed.
Within the Web UI of the unit, navigate to Configuration / Network / Advanced Network Settings. The Base Socket is listed in a field in the Network Service Settings section at the bottom and may be changed, to change the Telnet and Raw TCP/UDP port numbers.
The default Base Socket number is 2000. Because of that, the default Telnet TCP Port is 2001 (Base Socket + 1) and the default Raw TCP Port is 2101 (Base Socket + 101).
If you want a certain TCP/UDP port number to be used for the Telnet or Raw port, for example port 1000, follow these rules:
For Telnet: Subtract 1. So, use Port 999 as the Base Socket.
For Raw: Subtract 101. So, use Port 899 as the Base Socket.
May 15, 2019