By default, OpenLNS and LNS use port 6001 and 6002. This might cause conflict with other applications and might need to be changed.
You can modify the ports used by the POET server and clients by modifying the "Services" file (%WINDIR%\System32\Drivers\Etc\Services) using a text editor like Wordpad.exe or Notepad.exe.
For example, to change the POET port numbers to 7001 and 7002, add/modify the following lines in the "Services" file. The '#' in the example indicates that the following text is a comment.
poet 7001/tcp #FastObjects services
_poet 7002/tcp #FastObjects services
In addition to the services file, ports in the ptserver400.cfg file also needs to be modified. The ptserver400.cfg file is located in the LonWorks\bin folder
Add the following line into ptserver400.cfg file in the [servers\ptserver] section (the example use 7001 and 7002 but otherwise specify the first port of the 2):