Upgrade your routerOs to 5.10 or higher to fix this bug. What's new in 5.10 (2011-Dec-09 11:49): *) snmp - provide extended interface statistics when availabe; *) dhcpv6 client - use link-scoped multicast address; *) dhcp client - renew dhcp lease on ethernet link up event; *) ipv6 gre tunnel added ...