After upgrading Windows to 8.1 remote connections from my Macintosh using Remote Desktop Connection seized to function. The symptom is, when trying to connect, it complains as follows: “Remote Desktop Connection cannot verify the identity of the computer that you want to connect to”.
There are two workarounds for this.
No. 1: Install the new Client from the Mac AppStore. It works, but I don’t like it because of two annoying flaws. First of all, it opens my present .rdp-Files but doesn’t understand them and throws an error. Second, if it’s in fullscreen mode, unlike with the old client, the Macintosh Dock is not accessible anymore.
No. 2: Set two group policies, as described here by VMware:
This can be done locally or on the Active Directory Domain Controller (I’m successfully using the latter method). According to Microsoft, this is less secure, in theory.