If you have changed the device configuration to set it in bridged mode, or have initially configured it in bridge mode, OpenVPN will not work as expected behind another router or firewall, and will require a few configurations.
The first configuration requirement will be specify the router or firewall that sits in front of the NG Firewall. By going to Config > Network > Hostname, you will choose either Use Manually Specified Address and list the IP/Hostname of the router or firewall in front of the NG Firewall, or configured Dynamic DNS Service Configuration.
The second configuration requirement will be to set a forward on the router or firewall that sits in front of the NG Firewall to the NG Firewall on port 1194, which is the port that OpenVPN runs on. This will allow OpenVPN to connect to the NG Firewall and the network itself without being blocked by the front router or firewall.Follow