I can't answer your question on the dits, although it looks to me to be an intermittent cable and most
likely nothing in the settings.
As for COM1, you need to take into account that the COM1 pinout is "backwards" from COM2. Look at
the manual for details. A null-modem should work.
I am not sure why you are using a serial to USB converter. If you have the USB cable plugged into your RRC,
just use the virtual serial port under Windows (turn COM1's USB support on in the settings). If you want to
use a serial cable (the converter) instead, then turn USB support off and make sure you have a null-modem
adapter.
73,
Mitch DJ0QN / K7DX