I was asked to turn on NLA on a couple of servers because they were failing security scans. I did so, and am now unable to connect via RDP to these servers. I am on Windows 7 SP1, and the client supports NLA. I even upgraded to the Windows 8 RDP client, and the same thing still happens. I also cannot connect from any other Windows 2008 R2 or Windows 2012 servers.
So, being completely unfamiliar with NLA and not finding a lot on Google, what needs to be done so that I can connect to these servers using RDP?