Hello, it seems the endpoint manager (and possible other pages in freepbx) reference external CSS files. For example:
It is best practice to failover to another CSS file or render some kind of default font. We came across an issue where the devices accessing the FreePBX GUI would not render certain icons correctly. After troubleshooting, we noticed it was attempting to connect to these external CSS references. The devices did not have internet access and therefore were unable to render some of the icons/buttons.