Error response from daemon: ... connection refused

Hi, I’m quite new to Docker and, to get familiar with it, I have explored a few tutorial simple projects.
Unfortunately now Docker doesn’t work anymore and I find constantly the following error, even with the ‘docker pull hello-world’ command:

Error response from daemon: Get “https://registry-1.docker.io/v2/”: dial tcp: lookup registry-1.docker.io on [::1]:53: read udp [::1]:53861->[::1]:53: read: connection refused

In order to recover Docker, I have tried, unsuccessfully, to remove all containers, images and volumes and reinstalling Docker.

O.S.: Manjaro Linux

Any idea to recover a correct operation of Docker?
Thanks in advance.