The most common scenario is that the client has the CredSSP update installed, and the Encryption Oracle Remediation policy setting does not allow an insecure RDP connection to a server that does not have the CredSSP update installed.
To work around this issue, follow these steps:
- On the client has the CredSSP update installed, run gpedit.msc, and then browse to Computer Configuration > Administrative Templates > System > Credentials Delegation in the navigation pane.
- Change the Encryption Oracle Remediation policy to Enabled, and then change Protection Level to Vulnerable.