我有一个奇怪的问题，http://docs.gitlab.com/在几种不同的浏览器、ISP（使用移动数据和 wifi）、笔记本电脑、手机等上测试后，chrome 上出现了 ERR_CONNECTION_TIMED_OUT ...所有这些都出现了这个错误。（所以不可能是防火墙问题或其他问题）。
所有 gitlab.com | about.gitlab.com | ... 也都能正确加载。
nslookup docs.gitlab.com
Server: 1.0.0.1
Address: 1.0.0.1#53
Non-authoritative answer:
Name: docs.gitlab.com
Address: 35.185.44.232
ping docs.gitlab.com
PING docs.gitlab.com (35.185.44.232): 56 data bytes
64 bytes from 35.185.44.232: icmp_seq=0 ttl=101 time=234.375 ms
64 bytes from 35.185.44.232: icmp_seq=1 ttl=101 time=232.418 ms
64 bytes from 35.185.44.232: icmp_seq=2 ttl=101 time=233.903 ms
curl docs.gitlab.com
curl: (7) Failed to connect to docs.gitlab.com port 80: Operation timed out
Gerald 在评论部分表示，发生这种情况可能是因为 docs.gitlab.com 不支持 ipv6，但 github.com 也不支持 ipv6，但对我来说加载正常。
https://ready.chair6.net/?url=docs.gitlab.com https://ready.chair6.net/?url=github.com
从我的服务器：
traceroute -p 80 docs.gitlab.com
traceroute to docs.gitlab.com (35.185.44.232), 64 hops max, 52 byte packets
1 * * *
2 static.225.198.9.5.clients.your-server.de (5.9.198.225) 111.350 ms 106.862 ms 104.060 ms
3 static.129.2.99.88.clients.your-server.de (88.99.2.129) 106.229 ms 105.674 ms 110.266 ms
4 core24.fsn1.hetzner.com (213.239.229.141) 115.433 ms *
core23.fsn1.hetzner.com (213.239.229.137) 108.444 ms
5 core1.fra.hetzner.com (213.239.203.153) 117.755 ms
core1.fra.hetzner.com (213.239.229.77) 113.209 ms 110.851 ms
6 142.250.160.234 (142.250.160.234) 109.509 ms 110.020 ms 113.523 ms
7 232.44.185.35.bc.googleusercontent.com (35.185.44.232) 208.630 ms 206.959 ms 207.112 ms
从我家的连接：
traceroute -p 80 docs.gitlab.com
traceroute to docs.gitlab.com (35.185.44.232), 64 hops max, 52 byte packets
1 192.168.1.1 (192.168.1.1) 3.068 ms 2.659 ms 5.253 ms
2 5.238.26.1 (5.238.26.1) 14.396 ms 16.787 ms 21.767 ms
3 10.51.242.73 (10.51.242.73) 41.912 ms 20.850 ms 18.791 ms
4 10.51.242.74 (10.51.242.74) 26.811 ms 15.497 ms 17.607 ms
5 10.202.7.19 (10.202.7.19) 20.166 ms 17.263 ms 20.668 ms
6 10.202.7.18 (10.202.7.18) 17.967 ms 22.312 ms 16.737 ms
7 10.201.47.186 (10.201.47.186) 25.609 ms 24.143 ms 32.804 ms
8 et-10-0-6-0.ffttr6.frankfurt.opentransit.net (193.251.154.203) 105.352 ms
85.132.90.157 (85.132.90.157) 100.037 ms
85.132.90.169 (85.132.90.169) 101.856 ms
9 72.14.214.52 (72.14.214.52) 136.799 ms
193.251.252.246 (193.251.252.246) 137.395 ms *
10 72.14.212.229 (72.14.212.229) 164.663 ms 369.099 ms
232.44.185.35.bc.googleusercontent.com (35.185.44.232) 391.888 ms