x11vnc password check failed

as far as i can tell, everything is configured correctly. the service file is as follows:

[Unit]
Description=Start x11vnc at startup
After=multi-user.target

[Service]
Type=simple
ExecStart=/usr/bin/x11vnc -auth guess -display :0 -forever -loop -noxdamage -repeat -rfbauth /etc/x11nvc.pass -rfbport 5900 -shared
ExecStop=/usr/bin/killall x11vnc
Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target

the password is stored in /etc/x11vnc.pass using sudo x11vnc -storepasswd /etc/x11vnc.pass. i have reloaded the daemon: sudo systemctl daemon-reload and enabled the service: sudo systemctl enable x11vnc, and started the service sudo systemctl start x11vnc. on reboot, the service comes up just fine, but when i attempt to access it with VNC Viewer, after entering the correct password, i simply get a password check failed error: here's the kink: when i go to the machine itself and open the x11vnc utility, once i check the Allow Connections button, everything works just fine. problem is, this is an unattended kiosk panel and we can't be doing that everytime it restarts... because it's on the other side of the country. system is Debian 10.13 Buster and there is no firewall running yet. can someone kindly point out what i am missing?