Cannot read/write using 3rd party terminal to Arduino nano BLE board

I was trying to communicate with Arduino nano BLE board using Microsoft c# example (also other terminal). Both works fine with FTDI based device but not with Arduino nano BLE which base on nRF chip. Arduino nano BLE works fine with Arduino built-in SerialMonitor. I cannot even send data - it hangs up.
See Microsoft code compiled as Console App (.NET) :SerialPort Class (System.IO.Ports) | Microsoft Docs
Even Arduino BLE sends data continuously - nothing is received. On SerialMonito it works.
Worth to mention - ArduinoBLE is listed as USB Serial Device (usbser) ,and FTDI - as USB Serial Port.
Microsoft refers usbser to the code from the link above.
Where is the catch?

I would suggest using Putty or TeraTerm or Termite to verify operation before writing C# code.


Problem sorted out. Arduino nano BLE requires DTR and RTS signals to be On. Then it works like FDTI.