Two WANs - one supports IPv4 and 6, the other only IPv4
I would like to run my two WANs in a failover configuration. The main WAN is working with both IPv4 and 6, the second WAN is my backup and only supports IPv4. If the first WAN fails completely, what happens to the IPv6 traffic from the LAN trying to get out? I assume there is nowhere for pfSense to send IP6 traffic at that point but are there any options to invalidate the IP6 settings for clients and force them to start getting IP4 addresses for everything? Or, am I better off to disable IP6 altogether until both WANs support it?