Para executar as configurações abaixo é necessário ter o pacote IPv6 ativado.

Criar o Pool de IPs.

/ipv6 pool
  add name=ipv6_cliente prefix=X:X:X::/NN prefix-length=64

Configurar o IPv6 na interface WAN e na LAN. Na LAN ele deve pegar do Pool de IPs criado acima.

/ipv6 address
  add address=X:X:X::X/126 interface=ether1
  add address=::1 from-pool=ipv6_cliente interface=bridge1

Configurar o ND (Neighbord Discovery).

/ipv6 nd
  set [ find default=yes ] advertise-dns=yes other-configuration=yes

Configurar a rota default.

/ipv6 route
  add distance=15 gateway=X:X:X::X
  add distance=10 type=unreachable dst-address=X:X:X::/NN

Também é necessário configurar as regras de firewall para IPv6.

/ipv6 firewall filter
  add action=accept chain=input comment="Libera conexoes estabelecidas e relacionadas" connection-state=established,related
  add action=accept chain=input comment="Libera multicast" src-address=ff00::/8
  add action=accept chain=input comment="Libera link local" src-address=ff10::/10
  add action=accept chain=input comment="Libera multicast" dst-address=ff00::/8
  add action=accept chain=input comment="Libera link local" dst-address=ff10::/10
  add action=accept chain=input comment="Libera icmp" in-interface=ether1 limit=200,5:packet protocol=icmpv6
  add action=drop chain=input comment="bloqueia tudo" in-interface=ether1
  add action=accept chain=forward comment="Libera conexoes estabelecidas e relacionadas" connection-state=established,related
  add action=accept chain=forward comment="Libera icmp" in-interface=ether1 limit=200,5:packet protocol=icmpv6
  add action=drop chain=forward comment="bloqueia tudo" in-interface=ether1