PowerDNS Recursor returns SERVFAIL with wan-load-balancer

@jimloko and only… for TCP connections.
For UDP only a connection tracking router can do the load balancing, not a local machine as far as I remember.
You will need a local DNS server or to define some kind of LB logic that will only do fail over but will use all known UDP traffic from one interface via a single upstream router.

I had the same problem and being new to VyOS, it took me some time to find a solution. I solved it with enable-local-traffic and a load balancer rule:

        rule 11 {
            destination {
                port 53
            }
            failover
            inbound-interface lo
            interface eth0 {
                weight 2
            }
            interface eth3.50 {
            }
            protocol udp
        }

eth0 and eth3.50 are my WAN interfaces.