win10 1803 启用 hyperV 宿主机无法通过 dhcpv6 获得 ipv6 地址

dhcpv6 服务端为 dnsmasq 配置如下：

dhcp-authoritative
domain-needed
localise-queries
read-ethers
bogus-priv
expand-hosts
server=/lan/
dhcp-leasefile=/tmp/dhcp.leases
resolv-file=/tmp/resolv.conf.auto
addn-hosts=/tmp/hosts
conf-dir=/tmp/dnsmasq.d
stop-dns-rebind
rebind-localhost-ok
dhcp-broadcast=tag:needs-broadcast
dhcp-range=lan,192.168.1.100,192.168.1.249,255.255.255.0,12h
no-dhcp-interface=eth0.2
dhcp-range=fd11:4401::100, fd11:4401::200, 64, 12h
enable-ra

win10 1803 未启用 hyperV 时可正常获取 ipv6 地址，启用之后并新建 external vswitch，宿主机和客户机都会通过这个 vswitch 和物理网路桥接来和外部网络通信。此时 vswitch 无法获得 ipv6 地址，但 ra 正常可以获得 ipv6 前缀长度和缺省路由以及 dns 等等。而且此时客户机也正常，可以和外部 ipv6 通信。

用以下步骤尝试解决未果：
1. netsh interface ipv6 reset 重置网络配置
2. 完全关闭 win10 内建防火墙

通过抓包发现宿主机可以正确发出 dhcpv6 的请求，但好像没有收到回应一样多次重试请求：

11:46:18.204794 IP6 fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 solicit
11:46:18.207006 IP6 fe80::20c:43ff:fe28:80a6.dhcpv6-server > fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client: dhcp6 advertise
11:46:18.231870 IP6 fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 solicit
11:46:18.233859 IP6 fe80::20c:43ff:fe28:80a6.dhcpv6-server > fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client: dhcp6 advertise
11:46:19.246108 IP6 fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 solicit
11:46:19.247919 IP6 fe80::20c:43ff:fe28:80a6.dhcpv6-server > fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client: dhcp6 advertise
11:46:20.254656 IP6 fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 solicit
11:46:20.256491 IP6 fe80::20c:43ff:fe28:80a6.dhcpv6-server > fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client: dhcp6 advertise
11:46:22.257985 IP6 fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 solicit
11:46:22.259784 IP6 fe80::20c:43ff:fe28:80a6.dhcpv6-server > fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client: dhcp6 advertise
11:46:26.257935 IP6 fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 solicit
11:46:26.259782 IP6 fe80::20c:43ff:fe28:80a6.dhcpv6-server > fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client: dhcp6 advertise
11:46:34.276753 IP6 fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 solicit
11:46:34.342910 IP6 fe80::20c:43ff:fe28:80a6.dhcpv6-server > fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client: dhcp6 advertise
11:46:50.290112 IP6 fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client > ff02::1:2.dhcpv6-server: dhcp6 solicit
11:46:50.292013 IP6 fe80::20c:43ff:fe28:80a6.dhcpv6-server > fe80::e1ef:3ab8:4f9d:69ca.dhcpv6-client: dhcp6 advertise