Hi Bucher,
The Most popular operation mode is RealCOM. In this mode user is mapping virtual COM port by Nport Windows Driver Manager software on computer
Fallowing conditions must be met to make connection:
-Nport set to RealCOM mode
-IP address of Nport and PC must be in the same network subnet
-Firewall in OS must allow outgoing connection with destination TCP ports: 950+x(max.16), 966+x(max. 16).
-Virtual COM port mappedon OS by Nport Windows Driver Manager or Nport Administrator
You can also find description in below producer technote:
https://www.moxa.com/getmedia/90269b7f-b656-41b7-8b9c-94e030761b28/moxa-real-com-mode-for-nport-tech-note-v1.1.pdf