Note: *if you can't upload the font files, it means they are blocked on that server, you can check out this article to unblock them:
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Sorry, you are not allowed to upload this file type.

If you uploaded a custom font in a Divi module but it's not loading, then it's likely to be an issue with the font format.

Always make sure to upload both ttf and otf versions of the font file for maximum browser compatibility. To do it, first go to https://convertio.co/ and convert the ttf font file you may have to otf version (or vice versa).

Once converted, upload both the files for a font in a module, like this:

You need to press CTRL Key (Command Key for Mac) to select both versions of the font while uploading. OR, you can click on CHOOSE FONT FILES button two times to upload both versions of the font.

Do make sure that ALL is selected in supported font weights.

After these steps, you can apply this font to various elements on your website and it will work fine.