remote procedure call failed and did not execute

Good day.

Can any one please help.

I dunno if Im on the right place here.

I got server 2012 std running as the host Os (with ad and dns and dhcp) and then a terminal server running server 2012 std (just desktop experience)as well on hyper-v.

soon as the amount of remote desktop connections hit 14 users the rest of the user trying to login get the following error:

the remote procedure call failed and did not execute

I have reinstalled both OSs and reconfigured them still the same issue.

the server are not even using a lot of resources they both idle at 20 - 40% memory and cpu usage.