Question

新建 /etc/apt/sources.list.d/ros2-latest.list，内容为：

你的Debian/Ubuntu版本: Debian 9 (Stretch) Debian 10 (Buster) Ubuntu 16.04 LTS Ubuntu 18.04 LTS Ubuntu 20.04 LTS

deb https://mirrors.tuna.tsinghua.edu.cn/ros2/ubuntu/ {{release_name}} main

然后再输入如下命令，信任 ROS 的 GPG Key，并更新索引：

sudo apt install curl gnupg2
curl -s https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | sudo apt-key add -
sudo apt update

Reference: https://index.ros.org/doc/ros2/Installation/Crystal/Linux-Install-Binary/

Answer 1

阿里云的ros2镜像源下载也快，试试看：
https://developer.aliyun.com/mirror/?utm_content=g_1000303593