I opened an support ticket on getting IPv6 Virtual IP that will allow me to place a URL to internal IP address for web servers.  2.5.2021, Fortinet L2 engineer wrote up a NFR for my URL Virtual IP request for IPv6.    FutureCon is looking into a IPv6 talk.  I moved the Ubuntu DHCP and DHCPv6 back to the Fortinet because IA-NA and IA-PD need DHCPv6.  

I got rid of AT&T.  They gave me only one /64 PD.  Against all better judgment I switched to Comcast.   doubled my download speed and 1/3 the price.  Bought a Arris SB8200 3.1 modem.  

config system interface
  edit "wan2"
    config ipv6
      set ip6-mode dhcp
      set ip6-allowaccess ping
      set dhcp6-prefix-delegation enable
      set dhcp6-prefix-hint ::/60
config ipv6
set ip6-mode delegated
set ip6-allowaccess fabric
set ip6-reachable-time 30000
set ip6-retrans-time 3000
set ip6-send-adv enable
set ip6-manage-flag enable
set ip6-other-flag enable
set ip6-upstream-interface "wan2"
set ip6-subnet ::9:xxxx:xxxx:xxxx:xxxx:/64
config ip6-delegated-prefix-list
edit 1
set upstream-interface "wan2"
set subnet 0:0:0:9::/64
set rdnss-service default

Subnets start at 0-9 and A-F.
xxxx:xxxx:xxxx:xxxx can be assigned to the EUI-64 mac address. Mac: 00-09-0F-FE-00-01 so you would do 0009:0FFF:FEFE:0001.  

The first /64 subnet is set ip6-subnet ::xxxx:xxxx:xxxx:xxx/64 with set subnet ::/64 in the delegated edit 1 section at the bottom

set ip6-subnet ::9:xxxx:xxxx:xxxx:xxxx:/64 would be the 10th /64 subnet and you change the delated edit 1 section at the bottom to set subnet 0:0:0:9::/64

diag ipv6 address list will display the ipv6 gateways.  It will drop leading zeros.