Randomly get: gpg: keyserver receive failed: Cannot assign requested address

I want to add new repositories on Ubuntu 18.04 and randomly get the following error:

gpg: keyserver receive failed: Cannot assign requested address

Randomly, as in, the same command sometimes works and sometimes doesn't. When it doesn't, I just rerun it and eventually it works.

I've seen related questions, like this one but there are no satisfactory solutions. I didn't have this problem is the last few weeks, so something must have changed. On my side I believe nothing has changed, there are no reports that the keyserver is down or degraded, so I'm at a loss...

To reproduce this issue using docker:

1. Run docker run -it --rm ubuntu:18.04
2. In the docker container, run: apt update && apt install gnupg2 -y
3. Try to add the repository key, this one is from ROS Spanshot: apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 4B63CF8FDE49746E98FA01DDAD19BAB3CBF125EA, you may also try the key to Git PPA repository: apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys A1715D88E1DF1F24

The last step often fails with:

Executing: /tmp/apt-key-gpghome.FhnZLWMBd1/gpg.1.sh --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 4B63CF8FDE49746E98FA01DDAD19BAB3CBF125EA
gpg: keyserver receive failed: Cannot assign requested address

But if I rerun the same command, it will eventually work and output:

Executing: /tmp/apt-key-gpghome.x0bEOm55IF/gpg.1.sh --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 4B63CF8FDE49746E98FA01DDAD19BAB3CBF125EA
gpg: key AD19BAB3CBF125EA: public key "ROS Spanshot builder <rosbuild@ros.org>" imported
gpg: Total number processed: 1
gpg:               imported: 1