Everything should be server assigned.

What are the options in the IPV6 setup dropdown?

Off, 6in4, 6to4, DHCPv6-PD. If I select DHCPv6-PD it shows a dialog wanting to open incoming UDP ports 547,546...

Ok, enabled with DHCP, changed the LAN settings to Stateful mode and it's all running IPv6 now... Thanks.

Yup DHCP6-PD is the correct one to use.

Trying to get the same exact thing working with a FortiGate-50E. Does anyone have any pointers here?

I've tried DHCP and PPPoE addressing modes, PPPoE being the same way I receive a valid and working IPv4 address to no avail.

My tested configuration is as follows:

akl-fwl-01 # show sys int ufb
config system interface
edit "ufb"
set vdom "root"
set mode pppoe
set allowaccess ping
set scan-botnet-connections block
set estimated-upstream-bandwidth 1024000
set estimated-downstream-bandwidth 512000
set role wan
set snmp-index 6
config ipv6
set ip6-mode pppoe
set ip6-allowaccess ping
set dhcp6-prefix-delegation enable
end
set username "<snip>"
set password ENC <snip>
set mtu-override enable
set interface "wan1"
set vlanid 10
next
end

akl-fwl-01 (ufb) # config ipv6

 

akl-fwl-01 (ipv6) # set
ip6-mode Addressing mode (static, DHCP, delegated).
ip6-allowaccess Allow management access to the interface.
ip6-send-adv Enable/disable send advertisements flag.
ip6-reachable-time Reachable time (milliseconds; 0 means unspecified).
ip6-retrans-time Retransmit time (milliseconds; 0 means unspecified).
ip6-hop-limit Hop limit (0 means unspecified).
autoconf Enable/disable address auto config.
dhcp6-prefix-delegation Enable/disable DHCPv6 prefix delegation.

 

akl-fwl-01 (ipv6) # set ip6-mode
static Static setting.
dhcp DHCPv6 client mode.
pppoe IPv6 over PPPoE mode.
delegated IPv6 address with delegated prefix.