Hello,
To add multiple subnets behind a FortiGate device in a Meraki site-to-site IPsec VPN configuration, you need to make some changes in both the Meraki Dashboard and the FortiGate configuration. Here are the general steps you can follow:
- Log in to the Meraki Dashboard (dashboard.meraki.com) and navigate to the organization and network where the VPN is configured.
- Go to the "Security & SD-WAN" section and select "Site-to-site VPN" from the left menu.
- Locate the existing VPN connection with the FortiGate and click on its name to edit the settings.
- In the "Remote Subnets" section, add the additional subnets that are behind the FortiGate. Enter the subnet IP and subnet mask for each subnet you want to include. These subnets should match the ones you added in the FortiGate configuration.
- Save the changes.
Example below: