ルータのログがこんな感じだから待ってみるしかなさそう
Apr 23 19:32:24 [LOG]|DHCPC| Using a RA lifetime of 0 seconds on br-lan

Apr 23 19:32:27 [LOG]|DHCPC| Got DHCPv6 request

Apr 23 19:32:27 [LOG]|DHCPC| A default route is present but there is no public prefix on br-lan thus we don't announce a default route!

ipv6をつかってるところなんてほとんどないしipv4が繋がれば困らないんだけどね