Sometimes clients are having trouble contacting your WSUS or can contact them but do not report their status.
In the most cases, you would clean the Windows Update cache, reset the network connections and restart all services.
But especially with Windows 10 this is sometimes not enough.
I have found clients, which would not work after all. The problem is, that -for whatever reason- the service type has changed and this causes the reporting to fail.
To change this, open an elevated command prompt on the client and enter the command:
sc config wuauserv type= share
(Please note the space after “type=”!)
Warning: You are changing a system service. Test this in a testing environment first and proceed with caution.
Restart the computer and wait for the client to report to your WSUS.