Why ipv6 fail?

[loong]

XX-Net Status:

sys-platform: AMD64, Windows-10-10.0.18362

os-system: Windows

os-version: 10.0.18362

os-release: 10

os-detail: Version:10-0; Build:18362; Platform:2; CSD:; ServicePack:0-0; Suite:768; ProductType:0

architecture: 32bit,WindowsPE

browser: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.163 Safari/537.36

xxnet-version: 3.16.1

python-version: 2.7.17

openssl-version: 19.1.0 TLSv1_2 h2:alpn

lan-proxy: Disable

use-ipv6: auto

gws-ip-num: total:7 ipv4:0 ipv6:1

ipv4-status: OK

ipv6-status: unknown

connected-link: new:0

worker: h1:0 h2:0

scan-ip-thread-num: 10

ip-quality: 9999

is-idle: 0

proxy_state: OK

ca_state: OK

Appid_Working: false

Appids_Out_Of_Quota: false

Appids_Not_Exist: false

Using_Public_Appid: true