Having COMM ports on today's computers is very rare. Almost always have to install a comm card in the system. They are cheap, but would you not rather it be free? Damn right I would.
Here it is.
https://sourceforge.net/projects/com0com/ If you knew about it, but gave up because 64 bits required you must disable signed certs. Look again, it's fixed. That's right 64 bit drivers that are signed. Usable in 64 windows kernels. There is a 32 bit driver too.
Only downside, must be win 7 or better. Tried and failed XP.
Now you can install it and emulate end to end RS232 comms. It can even do chat groups over comm. Everybody talks to everyone else.