Automate VPN

HI all,

I'm trying to configure my Sophos UTM9 firewall to automatically switch the VPN to the secondary line if the primary line goes down.

I currently have two internet connections, with WAN1 (5.5.5.5) as the primary and WAN2 (7.7.7.7) as the backup. Right now, the VPN is configured to use the primary line (WAN1) as the peer address. If the primary line goes down, I have to manually switch the VPN to the secondary line (WAN2).

How can I automate this failover process?

Thanks

MW