Ubuntu server was recently closed its external network usage rights, but the installation of the software they need to connect to external networks, then it can only be connected through a proxy.
First Follow this post to set the proxy windows side.
Finally curl www.baidu.com to have printed.
But when I sudo apt-get update, the error still occurs
Unsupported proxy configured: 127.0.0.1://18088
Replace the temporary command:
sudo apt-get -o Acquire::http::proxy="
http://127.0.0.1:18088/" update
sudo apt-get -o Acquire::http::proxy="
http://127.0.0.1:18088/" install python3-pip
The results of a successful installation of the software