Send only outgoing traffic through VPN on Ubuntu server

Hi all! Need help setting up a VPN connection. I have a server on which Pritunl is deployed. I also have an Ubuntu server (let’s call it app_server) on which some websites are located. How can I make sure that all outgoing traffic from app_server goes through the VPN, while the sites on the app_server remain accessible via the Internet? I installed an openvpn client on app_server, connect it to the configuration openvpn --config /etc/openvpn/my-conf.ovpn --daemon, and everything works as it should, only my sites become inaccessible from the outside