Fonts not loading on subdomain

I’ve got a site with a default url structure like this: https://example.com.
Visitors attempting to go the http version are automatically redirected to https.
Using this url structure, everything works fine.

However, if the user manually enters ‘www’ into the url, the site will load with the url structure like this: ‘https://www.example.com’.

Using this structure, custom fonts will not load.

When I discovered this I went to the settings for the custom fonts I had set up.
I edited the urls to to protocol agnostic. ie…

‘//example.com/wp-content/uploads/…/fontname.woff’

I saved these settings and then revisited the site. The fonts still didn’t load.

How do I get the fonts to load properly?