Hi WSUAL2,
1. Apart from non-domain joined clients, does WSUS server with KB 3159706 work well for other clients?
2. On problematic clients, try resetting windows update components, check if it could work:
https://support.microsoft.com/en-us/kb/971058
3. If reset windows update component still doesn't work, also try reindex WSUS database on WSUS server and run server cleanup wizard:
https://technet.microsoft.com/en-us/library/dd939795(v=ws.10).aspx
(On server 2012 R2, the command is: SQLCMD -E -S np:\\.\pipe\MICROSOFT##WID\tsql\query -i <script location>)
Best Regards,
Anne
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