Dualstack

pkg_add dhcpcd-7.1.1p4

/etc/dhcpcd.conf
ipv6only
noipv6rs
duid
persistent
option rapid_commit
require dhcp_server_identifier

# disable running any hooks; not typically required for simple DHCPv6-PD setup
script ""

# List interfaces explicitly so that dhcpcd doesn't touch others
allowinterfaces em1 vlan108 vlan110 vlan112

interface em1
    # the following two lines tell dhcpcd to do router solicitation
    # itself. don't use them if using "inet6 autoconf" (slaacd)
    ipv6rs
    ia_na 1

    # request prefixes from the provider to use for downstream networks
    ia_pd 2 vlan108/1 vlan110/2 vlan112/3

rcctl enable dhcpcd
rcctl restart dhcpcd

/etc/rad.conf
interface em1

interface vlan112 {
  prefix 2a0b:2e00:0:7c03::/64
  dns {
    nameserver 2001:4860:4860::8888
    nameserver 2001:4860:4860::8844
    nameserver 2a0b:2e00:0:7c03::1
    search planet.noflow.ch
  }
}

rcctl enable rad
rcctl restart rad

module-config: "dns64 validator iterator"
dns64-prefix: 64:ff9b::/96

# NAT 64, all outgoing traffic from vlan 112
pass  in  log quick on vlan112 inet6 from any to 64:ff9b::/96 af-to inet from (egress)