N1MM+ config with RS232 vs USB COM1-what to prefer?

[Kari SM0HRP]

Hi folks,
I have been testing N1mm+ using USB COM1 and CW DTR-keying. New PC Win 7 (Optiplex) and RRC build V. 2.84. But I find the operation erratic. It works for a while but then looses coonection with the Virt COM Port (using COM1) quite regularly.  I have "cleaned" the PC from unused COM Ports with the Microbit device manager.
I have seen some using USB serial adapter between PC and RRC COM1. Does this work better? Can one get CW DTR keying in this case when RRC COM1 physical port seems to lack DTR pin?
I have also tried with physical PC serial COM Port conntected to RRC COM1 but get even here an erratic behaviour. 
73 Kari SM0HRP
P.S. It is in the details the devil is......D.S.

[Jan (Microbit)]

Since you are seeing erratic behaviour in both cases(USB and physical COM) I would suggest that you check if the RRC is rebooting itself when it looses the connection.