Hello,
As you have found out, a real COM port can't be shared by several applications at once, unless you use a Virtual Serial Port Emulator, such as VSPE:
https://eterlogic.com/products.vspe.html
The easiest way to solve this is to install OmniRig (
https://dxatlas.com/OmniRig/) and configure it for your transceiver. Either WSJT-X and of course Swisslog supports Omnirig. OmniRig handles the communication to the radio through the COM port but is sending the frequency and mode to the supported programs internally, no matter how many programs you are using at the same time. It's simple and effective with no conflicts. All this is explained as an important note in the Swisslog help contents:
Digital Modes Interfaces > Important about transceiver control (
https://www.swisslogforwindows.com/engli...rt.htm#CAT)
73