question
step by step according to the document, in fact, I have no problem walking down the Ubuntu server like this, and then in desktop
sudo add-apt-repository \
"deb [arch=amd64] https://download.docker.com/linux/ubuntu \
$(lsb_release -cs) \
stable"
when you find this step, you will make an error
W: Failed to fetch https://download.docker.com/linux/ubuntu/dists/bionic/InRelease Could not wait for server fd - select (11: Resource temporarily unavailable) [IP: 13.35.121.111 443]
W: Some index files failed to download. They have been ignored, or old ones used instead.
Ubuntu is 18.04