This is a really weird issue so bear with me.
The Google font I have uploaded (Playfair Display) isn’t rendering properly on some devices.
The only one I can replicate the issue on is a 2015 Macbook Air, 11 inch, with up-to-date Chrome, but Mac OS Sierra (so quite out of date).
On Chrome, the page loads but with no fallback font at all. The text just shows up as nothing.
On Safari, the page simply refuses to load.
The console makes me think this is a security issue that is blocking the font from loading?
But why won’t it load Google’s fallback font instead? As you can see, it makes the site unusable for some users!