MultiWAN unbound

[devilspgd]

Can anyone point me in the right direction to set up unbound to work across multiple WANs (specifically, to failover to the second WAN if the primary WAN becomes unavailable)

We flipped back to the built-in DNS forwarder this evening, it seems to be doing the job, but this requires a manual switch (and of course puts us back to forwarding, rather than resolving locally, which is less than ideal)