Preface

人在天朝，身不由己。何以解忧，唯有镜像。

Beginning

The problem of apt has trouble me for a long time. 我曾为此换到阿里云的镜像，但是不如清华的快。

Development

Several weeks earlier, I found the problem root from ipv6：mirrors.tuna.tsinghua.edu.cn 是自动解析，可能清华的镜像发现我是校园网，就以为我有 ipv6, 然而我并没有（此处鄙视南开校园网），所以就等、等、等 ¹，直到超时。

So the solution is to use mirrors4.tuna.tsinghua.edu.cn instead of mirrors.tuna.tsinghua.edu.cn when you can not connect to IPv6 (Especially inside NKU_WLAN):

sudo sed --in-place=.bak 's/mirrors\.tuna/mirrors4.tuna/' /etc/apt/sources.list

Climax

Then I get into trouble when I handle docker mirror. That lead me to find a better solution:

sudo apt -o Acquire::ForceIPv4=true ...

By the way, I successfully add deb repository for VSCode, slack, chrome, skype, sogoupinyin. Though it took me 2 hours and more, I thought update software automatically would benefit me a lot.

Epilogue

I think now I should have sloved the problem completely.