Sorry for the wrong link, senior moment.
Just been reaading the mail on th eorignal HC-05 "problem".
One poster made a comment on Windoze response - "Coupled" .
Never encountered such term in Bluetooth or Linux.
If true, talking about making -up own terminology .
Now this is little premature to mention, I like to get the hardware questions sorted out first , but
1. in the other tread they mentioned receiving unwanted characters or working at specific baud rate only
my guess it still goes back to understanding the serial communication protocol - not only baud rate but start / stop , parity etc.
2. as far as having tx -rx lines reversed in nanoVNA - could that be done in software much easier than in hardware ?
a question to the author of the software - will ask much later