Font awesome have now resolved the incident. Thanks for your patience.
Fontawesome seems to have fixed the core issue, and are waiting for things to recover.
Fonts in our application (we use fontawesome) are currently not displayed for some people right now. We're so sorry about that. Please standby for further updates, and we'll be in touch as soon as we know more.
Here's fontawesome's status page: https://status.fortawesome.com/