[user@hostname][13:21][/etc/systemd/system]
$ sudo systemctl start vncserver@:1.service
Job for vncserver@:1.service failed because the control process exited with error code. See "systemctl status vncserver@:1.service" and "journalctl -xe" for details.
[user@hostname][13:22][/etc/systemd/system]
$ systemctl status vncserver@:1.service
● vncserver@:1.service - Remote desktop service (VNC)
   Loaded: loaded (/etc/systemd/system/vncserver@.service; disabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Tue 2018-04-03 13:22:27 EDT; 4s ago
  Process: 35540 ExecStart=/usr/sbin/runuser -l DAM_VNC_User -c /usr/bin/vncserver %i -geometry 1280x768 (code=exited, status=1/FAILURE)
  Process: 35490 ExecStartPre=/usr/bin/vncserver -kill %i (code=exited, status=0/SUCCESS)
 Main PID: 29777 (code=exited, status=0/SUCCESS)

Apr 03 13:22:26 hostname systemd[1]: Starting Remote desktop service (VNC)...
Apr 03 13:22:26 hostname vncserver[35490]: Killing Xvnc process ID 33612
Apr 03 13:22:27 hostname systemd[1]: vncserver@:1.service: control process exited, code=exited status=1
Apr 03 13:22:27 hostname systemd[1]: Failed to start Remote desktop service (VNC).
Apr 03 13:22:27 hostname systemd[1]: Unit vncserver@:1.service entered failed state.
Apr 03 13:22:27 hostname systemd[1]: vncserver@:1.service failed.

$ sudo /usr/sbin/runuser -l VNC_User -c "/usr/bin/vncserver :1 -geometry 1280x768"

New 'hostname:1 (VNC_User)' desktop is hostname:1

Starting applications specified in /home/VNC_User/.vnc/xstartup
Log file is /home/VNC_User/.vnc/hostname:1.log

[Unit]
Description=Remote desktop service (VNC)
After=syslog.target network.target

[Service]
Type=forking
User=VNC_User

# Clean any existing files in /tmp/.X11-unix environment
ExecStartPre=-/usr/bin/vncserver -kill %i
ExecStart=/usr/sbin/runuser -l VNC_User -c "/usr/bin/vncserver %i -geometry 1280x768"
PIDFile=/home/VNC_User/.vnc/%H%i.pid
ExecStop=-/usr/bin/vncserver -kill %i

[Install]
WantedBy=multi-user.target