I have one Windows 10 Client that was communicating with my WSUS server (Server 2012 R2), and when I first installed the client it was communicating for several weeks, and then it has stopped communicating. I have tried a lot of troubleshooting, such as the following:
1. Ran RSOP.MSC and all the configuration are in order.
2. I can access the WSUS server from IE 11 on the client
3. Double checked the Registry and it does not seem to be an issue
4. Restarted the Client several times, and ran windows update manually. Windows update does work, and it does appear that it is receiving the updates from my WSUS server, and it is installing them, but my WSUS server states that the client has not checked in for 11 days.
5. Updates appear to be installing correctly.