unbound - DoT Servers with ipv6 address

[bringha]

High there,

I have a question around unbound and ipv6 based DNS servers:

I am running my sense behind a fritzbox with Telekom as ISP. The fritzbox acts as a gateway and is talking in ipv6 via Link local addresses (fe80: XXX ....) with the WAN interface of the Sense. I have configured DoT with unbound and from the sense itself, I can query directly the ipv6 addresses of the configured DoT servers. Also all ipv4 queries work fine.

Not so from LAN: when running unbound on debug level 4, I get the following error messages:

Code: [Select]

unbound[99672]: [99672:1] debug: iter_handle processing q with state QUERY TARGETS STATE
unbound[99672]: [99672:1] debug: servselect ip6 2606:4700:4700::1111 port 853 (len 28)
unbound[99672]: [99672:1] debug: servselect ip6 2606:4700:4700::1001 port 853 (len 28)
unbound[99672]: [99672:1] debug: servselect ip6 2620:fe::11 port 853 (len 28)
unbound[99672]: [99672:1] debug: servselect ip4 9.9.9.11 port 853 (len 16)
unbound[99672]: [99672:1] debug: servselect ip4 1.1.1.1 port 853 (len 16)
unbound[99672]: [99672:1] debug:    rtt=2494
unbound[99672]: [99672:1] debug:    rtt=2915
unbound[99672]: [99672:1] info: sending query: apple-dns.net. DS IN
unbound[99672]: [99672:1] debug: dnssec status: not expected
--> unbound[99672]: [99672:1] error: outgoing tcp: bind: Can't assign requested address
unbound[99672]: [99672:1] debug:    ip4 1.0.0.1 port 853 (len 16)
unbound[99672]: [99672:1] debug: attempt to get extra 3 targets
unbound[99672]: [99672:1] debug:    rtt=275
unbound[99672]: [99672:1] debug:    rtt=376
unbound[99672]: [99672:1] debug:    rtt=376
unbound[99672]: [99672:1] debug:    rtt=2494
unbound[99672]: [99672:1] debug: servselect ip4 1.0.0.1 port 853 (len 16)
unbound[99672]: [99672:1] debug: selrtt 275
unbound[99672]: [99672:1] debug: sending to target: <.> 2606:4700:4700::1001#853
--> unbound[99672]: [99672:1] error: outgoing tcp: bind: Can't assign requested address
unbound[99672]: [99672:1] debug:    ip6 2606:4700:4700::1111 port 853 (len 28)
unbound[99672]: [99672:1] debug:    ip4 1.1.1.1 port 853 (len 16)
unbound[99672]: [99672:1] debug: servselect ip6 2606:4700:4700::1111 port 853 (len 28)
unbound[99672]: [99672:1] debug: servselect ip6 2606:4700:4700::1001 port 853 (len 28)

When I delete all ipv6 addresses from the DoT list, there is no error message. Obviously, unbound can not contact the ipv6 DNS server from LAN via the gateway (see marked line) - but why ? 

I could imagine that this might be a config issue. Does anyone has an advice for me where to look into?

Thank you very much for your advice

BR br