How to share between Windows 11 and 10, over a specific cable?

Dear alt.comp.microsoft.windows,

How would I go about creating a shared folder, that is only shared
through the direct cable between my two computers?  I guess it's less
about the security, and more about the speed and convenience of not
having file transfers interrupt the internet traffic.

As far as I can tell, this is not discussed at all on the Microsoft
QA website, nor can I find anything with a casual websearch.

So, to break down the problem statement, I don't know how to

* configure the extra ethernet ports with a different local
   area subnet IP addresses,

* use those addresses to enable sharing only through said cable.


Is there a kind soul who can direct me to the right website or
knowledge base where this kind of setup is discussed?


I can provide an ASCII art diagram of my LAN if requested.
-- 
Johann | email: invalid -> com | http://www.myrkraverk.com/blog/
I'm not from the Internet, I just work there. | via Easynews.com