I faced really interesting problem – one of our servers stopped responding to RDP after server restart. I spent some time trying to troubleshoot it. This article from Microsoft gives good a course of troubleshooting. This one also can help. Unfortunalely, nothing helped in my case. Finally I opened a ticket with Microsoft. It took 4 hours to find the real root cause of the issue
First, we tried to install a hotfix, described here, but the installer hung up every time during the file backup. The further investigation showed, that if the Print Spooler service stopped, RDP worked just fine. Then we checked the
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Printers registry key and found a few keys for redirected printers, which was not deleted after server restart. Deleting these keys resolved the issue.