To use VPN resiliency/redundancy, configure a list of FortiGate IP/FQDN servers, instead of just one:
This is a balanced, but incomplete XML configuration fragment. All closing tags are included, but some important elements to complete the IPsec VPN configuration are committed.
This XML tag sets the IPsec VPN connection as ping-response based. The VPN connects to the FortiGate which responds the fastest.
By default, RedundantSortMethod =0, and the IPsec VPN connection is priority based. Priority based configurations tries to connect to the FortiGate starting with the first on the list.