Why does it say the port is busy? How to remove a port from a reserve?

Question

Java

Welcome all! I'm not sure that anyone can help, but hope dies last...
I want to finally deal with the problem that many people have...
There is a program "NCALayer", which is used in Kazakhstan for authorization on sites where an EDS key is required.
So, there is a PC on which the program does not always start correctly. Writes that the port (TCP) that the program uses (13759) is occupied by another program. Although through the monitoring of processes and ports, it is not visible that the port is busy ...
Reboot helps and the program starts, but the next time it may again give an error about the port being busy ...
Who can offer what? The program runs on java...

Normal program operation:


Error:


The port is not occupied by anything: