Ok so I worked with Nordvpn and if I run this:
openvpn /etc/openvpn/nordvpn/ovpn_udp/ch299.nordvpn.com.udp.ovpn
I connect but when I run dietpi-vpn with the same credentials it fails with:
[ OK ] DietPi-VPN | chmod +x /var/lib/dietpi/dietpi-vpn/static_up.sh /var/lib/dietpi/dietpi-vpn/static_down.sh
[ OK ] DietPi-VPN | umask 0077
[ INFO ] DietPi-VPN | Generating OVPN file, please wait...
[ OK ] DietPi-VPN | cp -f /etc/openvpn/nordvpn/ovpn_udp/ch299.nordvpn.com.udp.ovpn /etc/openvpn/client.ovpn
[ OK ] DietPi-VPN | umask 0022
[ OK ] DietPi-VPN | chmod 0600 /var/lib/dietpi/dietpi-vpn/settings_ovpn.conf /var/lib/dietpi/dietpi-vpn/settings_dietpi.conf /etc/openvpn/client.ovpn
[ OK ] DietPi-VPN | chown root:root /var/lib/dietpi/dietpi-vpn/settings_ovpn.conf /var/lib/dietpi/dietpi-vpn/settings_dietpi.conf /etc/openvpn/client.ovpn
[ OK ] DietPi-VPN | Setting in /etc/openvpn/client.ovpn adjusted: auth-user-pass /var/lib/dietpi/dietpi-vpn/settings_ovpn.conf
[ OK ] DietPi-VPN | Added setting script-security 2 to /etc/openvpn/client.ovpn after line auth SHA512
[ OK ] DietPi-VPN | Added setting up /var/lib/dietpi/dietpi-vpn/static_up.sh to /etc/openvpn/client.ovpn after line script-security 2
[ OK ] DietPi-VPN | Added setting down /var/lib/dietpi/dietpi-vpn/static_down.sh to /etc/openvpn/client.ovpn after line up /var/lib/dietpi/dietpi-vpn/static_up.sh
[ OK ] DietPi-VPN | sed -i /^[[:blank:]]*route-up[[:blank:]]/d /etc/openvpn/client.ovpn
[ OK ] DietPi-VPN | sed -i /^[[:blank:]]*route-pre-down[[:blank:]]/d /etc/openvpn/client.ovpn
[ INFO ] DietPi-VPN | Checking for required APT packages: openvpn
[ OK ] DietPi-VPN | systemctl restart dietpi-vpn
[FAILED] DietPi-VPN | Connection failed/timeout: ch299.nordvpn.com.udp.ovpn
[ OK ] DietPi-VPN | systemctl stop dietpi-vpn