Make sure your server is sending the font files with the right mime/type.
I recently have the same problem using nginx because some font mime types are missing from its vanilla /etc/nginx/mime.types file.
I fixed the issue adding the missing mime types in the location where I needed them like this:
location /app/fonts/ {
#Fonts dir
alias /var/www/app/fonts/;
#Include vanilla types
include mime.types;
#Missing mime types
types {font/truetype ttf;}
types {application/font-woff woff;}
types {application/font-woff2 woff2;}
}
You can also check this out for extending the mime.types in nginx: extending default nginx mime.types file