我系统里不支持 ipv6,怎么看上去是在连 ipv6?(还没有发现别的网站有这问题)
```sh
$ curl -vvv '
https://wanqu.co/'
* Trying 104.28.0.118...
* TCP_NODELAY set
* Trying 2400:cb00:2048:1::681c:76...
* TCP_NODELAY set
* Immediate connect fail for 2400:cb00:2048:1::681c:76: Network is unreachable
* Trying 2400:cb00:2048:1::681c:176...
* TCP_NODELAY set
* Immediate connect fail for 2400:cb00:2048:1::681c:176: Network is unreachable
* Trying 2400:cb00:2048:1::681c:76...
* TCP_NODELAY set
* Immediate connect fail for 2400:cb00:2048:1::681c:76: Network is unreachable
* Trying 2400:cb00:2048:1::681c:176...
* TCP_NODELAY set
* Immediate connect fail for 2400:cb00:2048:1::681c:176: Network is unreachable
* Trying 2400:cb00:2048:1::681c:76...
* TCP_NODELAY set
* Immediate connect fail for 2400:cb00:2048:1::681c:76: Network is unreachable
* Trying 2400:cb00:2048:1::681c:176...
```