Learn about content caching
With the right configuration, a significant amount of Apple content can be cached with the built-in Content Caching service in macOS. Content caching can minimize bandwidth usage and speed up the download of content distributed by Apple to your Apple devices.
When an Apple device requests content for the first time, the Content Caching service downloads the data from the internet and streams it directly to the device. When subsequent Apple devices request the same data, it’s served directly from the Content Caching service without consuming additional bandwidth. Because the local network is normally much faster than the internet, the second device (and all subsequent devices) will download updates much more quickly.
Content caching can be used on all networks, including those with complex routing, NAT, and multiple public IP addresses.