Change content caching preferences on Mac
Use the Content Caching pane of Sharing preferences to manage content caching on your Mac. You can turn content caching on or off, choose the items you want cached, set the cache size, and set up additional content caching options for your network. To learn more, see About content caching on Mac.
To change these preferences on your Mac, choose Apple menu 
> System Preferences, click Sharing, then select Content Caching.
Open Sharing preferences for me
Important: Each content cache must have either a local IP address that conforms to RFC 1918, or a non-RFC 1918 local IP address that is the same as its public IP address. Content caching is not supported on networks that use non-RFC 1918 addressing locally, and different non-RFC 1918 addressing publicly.
Local IP addresses that conform to RFC 1918 are in the following ranges:
10.0.0.0 to 10.255.255.255 (10/8 prefix)
172.16.0.0 to 172.31.255.255 (172.16/12 prefix)
192.168.0.0 to 192.168.255.255 (192.168/16 prefix)
Important: Content caching works only while your Mac is awake. To prevent your Mac from going to sleep, choose Apple menu > System Preferences, click Energy Saver, then select the “Prevent computer from sleeping automatically when the display is off” checkbox. To keep a headless computer awake, you can use the caffeinate command line utility in Terminal.
Content Caching | To turn content caching on or off, select or deselect the Content Caching checkbox in the service list. Content Caching status indicator colors:
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Cache | Select the items you want cached:
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Share | Select the Internet Connection checkbox to share the Internet connection and cached content with iOS devices connected to this Mac using USB. | ||||||||||
Options or Advanced Options | Click Options to set the cache size. Press and hold the Option key, then click Options, or click Advanced Options to set options for the cache size and content caching clients, peers, and parents. | ||||||||||