I recently had an issue where after a reboot, I could no longer connect to my Server 2016 server through RDP. file shares etc appeared fine.
To re-enable this remotely, I did the following steps from an elevated command prompt (Note, you will need pstools which can be downloaded here)
psexec \\remotemachine reg add "hklm\system\currentcontrolset\control\terminal server" /f /v fDenyTSConnections /t REG_DWORD /d 0
psexec \\remotemachine netsh advfirewall set service remoteadmin enable
psexec \\remotemachine netsh advfirewall set service remotedesktop enable