Hi Mathias.
IPv6 is not disabled by default on NethServer. You can find this out with:
ip a | grep inet6 # IPv6 enabled if returns any IPv6 address
sysctl -a | grep disable_ipv6 # IPv6 disabled if settings equals 1
Unbound doesnt start, IPv6 deaktivieren and unbound flooding syslog with ‘sendto failed: Cannot assign requested address’ links suggest the error could be due to IPv6 being disabled, and provide a solution by specifying interface: 127.0.0.1 in unbound config, but this setting is already applied by nethserver.
unbound[6913]: Oct 24 23:25:39 unbound[6913:0] error: cannot open control interface ::1 8953
Same is suggested for control-interface option when unbound remote control is enabled (enabled by default by upstream Unbound package and by NethServer but control-interface not explicitly specified).
If IPv6 was disabled (and must remain that way) by any particular reason, do-ip6: no unbound option could be of use.
/var/log/messages and jounalctl -u unbound might provide more clues about why the service does not start.
When trying any of the unbound options remember the conf file is templated.