Mogelijkheid kan zijn dat je Dual-Scan niet hebt uitgeschakeld.
Wanneer SCCM server niet bereikbaar is, worden updates via internet gedownload.
https://www.petri.com/what-is-wsus-dual-scan
Disable Dual Scan Policy Setting
Windows 10 users can manually click Check for updates in the Settings app, or the Check online for updates from Microsoft Update link, and a feature update could be applied to the device even if it wasn’t approved by IT. To prevent this happening, administrators often set the WUfB deferral policy to block feature updates installing as soon as they are released to Microsoft’s update servers. But setting the policy enables Dual Scan, and in the process, organizations lose control over the ability to approve quality updates via WSUS.
To address this situation, Microsoft added a new policy setting that can be enabled to stop Dual Scan being used if WUfB deferral policies are set in a WSUS environment.
Do not allow update deferral policies to cause scans against Windows Update
This setting allows organizations to configure WUfB and delay installation of feature updates while making sure the devices won’t scan Windows Update for quality updates.