Hello @Jcol7884,
You will need to install the security certificate on all devices that will need to access the encrypted cached content. Apple’s updates (as most vendors now) come through secure sites and get encrypted. It is like accessing a banking website at https.
This challenge you are experiencing exists across all manufactures & suppliers of caching/buffering systems.
You can find a copy of the process to install the certificates for apple device here on this URL
You can also find other guides for the MediaFast certificates within the form at the URL of Search results for 'Peplink MediaFast Certificate Installation @mldowling' - Peplink Community
Happy to Help,
Marcus 