Yep, did all that.
I’m completely stumped. I just have to assume it’s something that the hosting provider is doing… but I manage 8 other accounts with that host and they all run WordPress fine. Of course when I mention it they just blame WordPress.
I gave up anyways; luckily this is a really basic site for a local business so they’re not using a cart system or anything. Just built it line by line. Ah, the good old days.