"an error occurred while loading this content try again later" - this occurs with some movies and never fixes itself. Why?

There is no answer. This is a known bug that has hobbled AppleTV for years, and will continue to for years to come.

That's simply incorrect.

I really wish it were. However, having read many of the hundreds of threads on this site devoted to this topic, I see that there are infinite workarounds that one can try, which may or may not resolve problems, there is no actual solution to the overall problem.

If you know differently, I invite you to provide the solution. But from what I gather, there is no solution to provide.

These issues are often related to the network, but not knowing anything about the OP's setup and what has been tried it is hard to determine much of anything.

There are a number of reasons why this can occur, most of which are as a result of problems with the users network. It's obvious from your terminology that you don't accept this and therefore little point in debating it with you.

I didn't post to argue the point with you, rather to alert other users that your statement is incorrect.

For me, this isn't a network issue. Some movies play fine, others don't. The ones that don't play are MP4s, just like the ones that do play. I have "tried again later" as the error message suggests, to no avail.