How to add a separate IPv6 address for the LXC container?

I have a VPS that supports IPv6, provided by the merchant a /64 IPv6 subnet per server.

But how should I configure it to the LXC container?

This is my environment

root@lxc:~# cat /etc/network/interfaces
# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
address 172.x.x.x
netmask 255.255.255.0

gateway 172.x.x.1
iface eth0 inet6 static
	accept_ra 0
	address 2604:fbc0:7b:031d:0000:0000:0000:0001
	netmask 64

	gateway 2604:fbc0:7b::1
post-up /sbin/ip -r route add 2604:fbc0:7b::1 dev eth0
post-up /sbin/ip -r route add default via 2604:fbc0:7b::1

root@lxc:~# cat /etc/resolv.conf
nameserver 8.8.8.8
nameserver 8.8.4.4
nameserver 2001:4860:4860::8888
nameserver 2001:4860:4860::8844

root@lxc:~# lxc network list
WARNING: cgroup v2 is not fully supported yet, proceeding with partial confinement
+--------+----------+---------+-------------+------+-------------+---------+
|  NAME  |   TYPE   | MANAGED |    IPV4     | IPV6 | DESCRIPTION | USED BY |
+--------+----------+---------+-------------+------+-------------+---------+
| eth0   | physical | NO      |             |      |             | 0       |
+--------+----------+---------+-------------+------+-------------+---------+
| lxdbr0 | bridge   | YES     | 10.0.0.1/24 |      |             | 1       |
+--------+----------+---------+-------------+------+-------------+---------+
root@lxc:~# lxc network show lxdbr0
WARNING: cgroup v2 is not fully supported yet, proceeding with partial confinement
config:
  ipv4.address: 10.0.0.1/24
  ipv4.nat: "true"
  ipv6.nat: "true"
description: ""
name: lxdbr0
type: bridge
used_by:
- /1.0/profiles/default
managed: true
status: Created
locations:
- none

root@lxc:~# ip route
default via 172.x.x.x dev eth0 onlink
10.0.0.0/24 dev lxdbr0 proto kernel scope link src 10.0.0.1 linkdown
172.x.x.0/24 dev eth0 proto kernel scope link src 172.x.x.x

root@lxc:~# ip -6 route
::1 dev lo proto kernel metric 256 pref medium
2604:fbc0:7b::1 dev eth0 metric 1024 pref medium
2604:fbc0:7b:31d::/64 dev eth0 proto kernel metric 256 pref medium
2604:fbc0:7b:31d::/64 dev lxdbr0 proto kernel metric 256 linkdown expires 3538sec pref medium
fe80::/64 dev eth0 proto kernel metric 256 pref medium
fe80::/64 dev lxdbr0 proto kernel metric 256 linkdown pref medium
default via 2604:fbc0:7b::1 dev eth0 metric 1024 onlink pref medium

root@lxc:~# lxc launch ubuntu/20.04 ubuntu
WARNING: cgroup v2 is not fully supported yet, proceeding with partial confinement
Creating ubuntu
The local image 'ubuntu/20.04' couldn't be found, trying 'ubuntu:20.04' instead.
Starting ubuntu
root@lxc:~# lxc list
WARNING: cgroup v2 is not fully supported yet, proceeding with partial confinement
+--------+---------+-----------------+------+-----------+-----------+
|  NAME  |  STATE  |      IPV4       | IPV6 |   TYPE    | SNAPSHOTS |
+--------+---------+-----------------+------+-----------+-----------+
| ubuntu | RUNNING | 10.0.0.9 (eth0) |      | CONTAINER | 0         |
+--------+---------+-----------------+------+-----------+-----------+
root@lxc:~# lxc exec ubuntu -- bash
WARNING: cgroup v2 is not fully supported yet, proceeding with partial confinement
root@ubuntu:~# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
6: eth0@if7: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 00:16:3e:41:4e:b8 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 10.0.0.9/24 brd 10.0.0.255 scope global dynamic eth0
       valid_lft 3582sec preferred_lft 3582sec
    inet6 fe80::216:3eff:fe41:4eb8/64 scope link
       valid_lft forever preferred_lft forever
root@ubuntu:~# ping6 www.gogole.com
ping6: connect: Network is unreachable