As of unbound 1.12.0 the AF_NETLINK is required during process startup
in some configurations. Without this patch the process startup
terminates as follows:
 unbound[10523:0] error: failed to list interfaces: getifaddrs: Address family not supported by protocol
 unbound[10523:0] fatal error: could not open ports
The requirement was first introduced  and only after the release
fixed in the upstream unit files . The upstream fix is the same fix
we are applying to our unit configuration.