Hello,
Please check in the SEPM >> Policies >> Liveupdate >> Liveupdate Policy.
Edit the Liveupdate Policy and Under Windows Settings >> Schedule
This Enables or disables clients to use the Symantec LiveUpdate server in addition to the Symantec Endpoint Protection Manager server. When this option is enabled, you can set the scheduling options that the clients use when they communicate with the Symantec LiveUpdate server.
This option is enabled by default.
Frequency - specifies how often to schedule clients to run LiveUpdate to download the latest updates. The default is Every four hours. The specific time option is available for both Daily and Weekly options. The specific day option is available for the Weekly setting only.
The Continuously option allows the client computers that infrequently communicate with the Symantec Endpoint Protection Manager server to get the latest updates. They get the latest updates when they connect to the network and authenticate to the server.
Note: On Mac clients, the Continuously option specifies that the client communicate with a LiveUpdate server once an hour.
Retry Window - specifies the number of hours or days to keep trying to run LiveUpdate if the scheduled run of LiveUpdate failed for some reason. This option is enabled when the Every, Daily or Weekly option is selected. The default is a two-hour retry window.
Note: Only Windows clients keep trying to run LiveUpdate. Retrying is not available for Mac clients.
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Hope that helps!!