My guess is that the RRC nano's serial port setting doesn't work and will work with com2 regardless of the value set. Because I set the com2 port status to "Inactive" in the serial port settings of radio 1258,After restarting radio 1258, check again that the state of serial port setting com2 is still "inactive".If RRC nano is connected to 1258 at this time, the port status of com2 will become "mode2 icom cvi".
Therefore, I conclude that the serial port selection of RRC nano is invalid.