> The main issue is that dhcp6c-state is not called: I do get an IPv6 address (without DNS), but radvd is not started and no route is advertised to my local network.

That change is fine.

> Feb 16 09:23:34 rdnssd[585]: Get IPv6 address & DNS from RA

You should probably contact your ISP and let them know they have their RA misconfigured (probably won't help, but it's worth a try). That message from rdnssd means that neither the Managed nor Other flags are set in the incoming RA. According to [RFC 4861](http://tools.ietf.org/search/rfc4861#section-4.2):

> Note: If neither M nor O flags are set, this indicates that no information is available via DHCPv6.

This is exactly the case when that rdnssd message gets printed. Clearly your ISP is providing DNS information via DHCPv6 and should have the Other flag set.

That said, I'm sure this will be a common misconfiguration. It seems like something that would be easy to overlook. And requesting DNS servers from DHCPv6 probably won't hurt. It seems like most of this code is still a work in progress. Most likely Asus was in the middle of implementing their changes, but pushed out the release because of security fixes. Note that even though they run rdnssd, they don't have any way to get DNS servers from it yet.