You are likely getting this error because you have the following checked off:

Allow connections only from computers running Remote Desktop with Network Level Authentication (recommended)

Uncheck this setting and you  will be able to log back in using RDP.

We got this error trying to add a secondary AD DC to a cluster.  After some troubleshooting, we removed this setting to allow us to login and complete the AD DC cluster. 

Unless your cluster is part of an AD DC, you will not be able to login with your AD credentials until you add it to a domain. 

Check,
TK