The problem of ‘Another device is using your IP address’ appears to be something entirely different than I had realized before

I have a background in software and hardware that goes back to at least 1966 and by 1968 I was studying both COBOL and FORTRAN which are early but effective computer languages. COBOL is a business language that is still used today in order to get programs to actually run faster than newer language programs tend to and FORTRAN (literally formula translation) often is better used by universities and research facilities many places because it is a more scientifically based language literally formula translation which reminded me a lot of studying Algebra when I learned this Computer language between 1966 and 1968.

But, I'm afraid I took literally that the problem was "someone else's computer stealing the address of my computer".

However, that doesn't seem to actually be the case when applied to Apple computer products according to this article but could just mean that your kid who is a gamer did this:

begin partial quote:

For instance, you might be running a game server or want to screen share with your computer remotely, have read up on port mapping or UPnP (Universal Plug ’n’ Play), and configured your machine to have a fixed (or “static”) private address so that it could always be reachable via some router magic. You might have, say, set your computer’s address to be 192.168.1.100.

end partial quote from:

https://www.macworld.com/article/234776/how-to-fix-your-network-when-you-see-another-device-is-using-your-ip-address.html 

And yes I have a son who has been building his own gaming computers since he was about 21 years old even though he is married with a wife and child now and almost 50 years old now. So, regarding gaming functionality he would know more about all this than I would simply because most of my computer knowledge though it goes back to 1966 or before I haven't really done justice to since I switched to Apple laptop computers like the Macbook Pro in the early 2000s. Why did I do this? I simply got tired of PC applications crashing all the time on PCs and Macs don't crash or usually get infected either. So, if you have a problem with your Mac computer likely you have to take it in to an Apple store to get it fixed which is very rare I find by the way.

The point being that PCs are the best gaming platform (and what most computer gamers use) not Apple products. Apple products are good at different things like Music and graphics and not crashing and the like but not usually gaming.

The point being that I might be getting this Another device is using your IP address’ simply because my son might have set up Screen sharing on this device or another one in my home which is kind of upsetting in itself that I was left with these error messages that pop up periodically. However, if you carefully read the last article about all the things this could be then you likely are as discouraged as I am about all this right now. Because it looks like it's more a problem to fix it than to leave it the way it is because it isn't usually a person (like a neighbor) stealing bandwidth and your IP address and committing crimes using your IP Address according to this article but instead it likely is all sorts of other things instead.

So, most people are just going to either say: "I don't have time to deal with this BS!" Or they hire someone else to fix their computer or local computer network and wifi which might or might not be the problem to begin with. And then you still might get this error message anyway and have wasted all that money in hiring someone who took your money without solving the problem because he didn't know what it was either.

Note: Have you ever been to an Auto shop where they fix your car and it says on a sign on the wall:

"IF it ain't broke don't fix it."

In all likelihood if you get this error message all the time like I do the above adage after restarting your computer from scratch might be the best idea (or not).