I suggest you to examine why using this particular custom CDN fails to load the font through SSL connection.
Also, as you can see the resource is requested from a non-SSL URL and thus, causing the cross-site access problem. So you should see why in an SSL-enabled connection, the resource is not handled properly. Note that in the configuration provided, the CdnSettings-BaseSecureUrl property is set to a non SSL URL. Try if correcting this resolves the issue.
With the Telerik CDN, using SSL, requests are properly handled and I am not sure what it might fail with using a custom one.
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