或sudo apt-get update会sudo apt install python3-pip导致错误。
我 ping 了 Google 和 Ubuntu 更新的 IP，一切正常
Connection failed [IP: 185.125.190.39 80]
Err:2 http://security.ubuntu.com/ubuntu focal-security InRelease
Connection failed [IP: 91.189.91.38 80]
Err:3 http://archive.ubuntu.com/ubuntu focal-updates InRelease
Connection failed [IP: 91.189.91.39 80]
Err:4 http://archive.ubuntu.com/ubuntu focal-backports InRelease
Connection failed [IP: 185.125.190.39 80]
Reading package lists... Done
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/focal/InRelease Connection failed [IP: 185.125.190.39 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/focal-updates/InRelease Connection failed [IP: 91.189.91.39 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/focal-backports/InRelease Connection failed [IP: 185.125.190.39 80]
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/focal-security/InRelease Connection failed [IP: 91.189.91.38 80]
W: Some index files failed to download. They have been ignored, or old ones used instead.
