Issue : SCCM 1606 All the reporting device are not getting patch.
Step 1: Verified Reported issue and study WUAHandler.log
After seeing WUAHandler.log log found most of the device are getting failed with subject line error code. refer below screen shot for reference
Step 2: Verified IIS Logs and found that none of the clients are getting communicate with sccm.
After validate multiple logs and events. Found last month there was KB have been applied. KB3159706 which is causing issue.
Refer this url for more details: https://blogs.technet.microsoft.com/wsus/2016/05/05/the-long-term-fix-for-kb3148812-issues/
This KB3159706 is fix for KB3148812 but issue reported kb was not part of these server hence we have removed KB [KB3159706] from the server and restarted and all the Patch start downloading and getting installed. refer below screen shot for reference.
Thanks & Regards,