I read the following
guide:https://help.fortinet.com/fos50hlp/52data/Content/FortiOS/fortigate-ipsecvpn-52/IPv6_and_IPsec/Site_Site_IPv6_over_IPv4_ex.htm#
The issue I have is that this only support single stack, either IPv4 or
IPv6 across the IPSEC t...