As we can read in this thread [0] dnsmasq doesn't permit to specify a custom mtu for ipv6, this is needed on out setup to avoid batman-adv level fragmentation, so the actual solution in dnsmasq doesn't work because it requires to put a lower mtu on specified interface and we cannot ( and don't want to do this ) Gui can you ask to dnsmasq developer to add this option so dnsmasq can work good also on our setup ? [0] http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2013q2/007160.html P.S. With al we have debuged some mtu iussue and committed fixes