Issue while Set up a ProxyVM as a VPN gateway

I have followed this guide Contents/vpn.md at master · Qubes-Community/Contents · GitHub
I have an issue in this step
sudo openvpn --cd /rw/config/vpn --config openvpn-client.ovpn

outputs:
[user@sys-vpn ~]$ sudo openvpn --cd /rw/config/vpn --config openvpn-client.ovpn

2022-04-25 18:50:59 Cipher negotiation is disabled since neither P2MP client nor server mode is enabled Options error: You must define TUN/TAP device (--dev) Use --help for more information.