I’m not saying that there’s not another way out of your predicament, but this sledgehammer approach has a high likelihood of success and requires no special knowledge. There are a bunch of tiny things that I might try if I were the one fixing it, but they are all rather difficult to describe here, especially when it’s unclear which one(s) to try or whether they might work.
If this system was set up in 2016 and still has that OS, then it’s not too soon to get an OS upgrade either, and IMHO it’s much easier to spin up a new server than to do an OS upgrade (that may be much less true now than it was 15 years ago when I formed that opinion!).