Hi,
Thanks for posting in Microsoft Q&A forum.
Per my experience, SCCM client should communicate with the site server in a regular period to complete specific tasks. For example, Client policy polling interval(15 minutes by default), State message reporting cycle (15 minutes by default), Polling interval for modern devices etc, we can customize these settings in client settings. This is normal if only a little bandwith traffic consumed.
Best regards,
Simon
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