So I've run into the problem now, trying to download
https://www.ti.com/lit/ug/scyd013b/scyd013b.pdf on my MacBook.
Here's what we can rule out as being individually responsible:
- ISP and LAN: it fails on the MacBook, but works on my iPhone, using the same Wi-Fi (with cellular data disabled to ensure the iPhone isn't failing over to cellular, which it will do normally), so in isolation, it's not the ISP or LAN.
HOWEVER, if I use my iPhone as a hotspot and let the MacBook tether to it, then it loads on the MacBook!!- browser choice: it's the same in Safari, Chrome, and Firefox
- OS: since it works when changing ISP, it can't be the OS
- browser configuration (cookies, extensions, etc): since it works when changing ISP, it can't be configuration
- JavaScript: same with JS on or off
- DNS: I tried with my ISP and Google DNS, no change
- TI policy: since it works when changing ISP or device, it's not policy. Moreover, not all PDFs seem to be affected. I can load other TI PDFs just fine.
- referrer: same result whether by clicking a link, pasting in the URL, or attempting to download the URL directly
So clearly this is a very, very, very narrowly triggered issue. If I had to guess, a router configuration error somewhere at TI which only rears its head when a particular route is selected, and gets cached somewhere by something.