Thanks for your reply. I tried everything mentioned I could find on the internet. Which is not saying much because the “s1001” seems to be a big mystery. I gave up trying to fix the problem. I switched to Linux. No more problem.
Here’s another summary of what was happening:
No new files were being played. In the logs, all files scanned supposedly had no video or audio codec. The original problem was that after one new file wouldn’t play, I did the “Plex Dance” with it and it still wouldn’t play. I then did it with the entire library and after that, no files in the library would play. The log said none of them had a video or audio codec. When trying to play them with the webapp, I got a s1001 Network error. There was no discernable network issue because files from other libraries would play. When I tried to play a “bad movie” with the Plex Apple Client, it said it couldn’t find it. Surprising , all the files in the same library played with the Nvidia client. In all the movie pages, the resolution and audio information had disappeared and in their place was the word “Unavailable”. The correct info was in the XML! I have posted this information in Facebook and previously in the forum. There have been no replies from Plex. I found a lot of dead-end threads that asked for help with the s1001 error with no replies whatsoever. There was only one known fix that worked. That was removing the URL from the Extras setting. This was not my issue so the fix did not apply. I also “fixed” file ownership and permissions and that was of no help.
I finally gave up and switched to Linux. The problem no longer exists and Plex is faster.