Check the system routing table

Browse to Diagnostics > Routes and review the routes known by the firewall. For site-to-site VPNs, routes will be present for the remote network(s) to the appropriate tun or tap interface. If the routes are missing or incorrect, the Local Network, Remote Network, or custom options are not configured correctly. If a shared key setup is in use and not PKI, ensure that “push” commands are not being used.