Hello there,
Can the servers reach the WSUS server on the required port?
Have you looked at "Get-WindowsUpdateLog" via PowerShell, any errors?
Please check the System event in Event Viewer to confirm if there is any related event has been logged.
Background Intelligent Transfer Service (BITS) is the service used by WSUS to download updates from Microsoft Update to the main WSUS server, and from WSUS servers to their clients. Some download issues may be caused by problems with BITS on the server or client computers. When you troubleshoot download problems, you should ensure that BITS is running properly on all affected computers.
Hope this resolves your Query !!
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