Most of the posts highlight what I am focused on and express work and personal experience. Reason I put them here - recall later or help someone else with similar challenge.
When RDP to Windows 2012R2 you may see the error like: Remote Desktop can't connect to the remote computer for one of these reasons.
I believe, that all listed reasons you can fix your-self, however there is one, that might be not obvious. It is number of concurrent connections, which is set to 1 by default. So to fix this we will need launch gpedit.msc and set limit connections properly.
Ok, now we need this:
Computer Configuration → Administrative Templates → Windows Components → Remote Desktop Services → Remote Desktop Session Host → Connections.
Next we need «Limit number of connections» either disable or enable and set Limit accordingly. Check video: