The following URL should be accessible on the Target Windows OS System for Online Patch Scan through SapphireIMS:
http://windowsupdate.microsoft.com
http://.windowsupdate.microsoft.com
https://.windowsupdate.microsoft.com
http://.update.microsoft.com
https://.update.microsoft.com
http://.windowsupdate.com
http://download.windowsupdate.com
https://download.microsoft.com
http://.download.windowsupdate.com
http://wustat.windows.com
http://ntservicepack.microsoft.com
https://.prod.do.dsp.mp.microsoft.com
http://.dl.delivery.mp.microsoft.com
https://*.delivery.mp.microsoft.com
https://tsfe.trafficshaping.dsp.mp.microsoft.com
Reference URL: Windows Update troubleshooting - Windows Deployment | Microsoft Docs