Problem demo

or how ping, docker and apt update all hit the same problem

> ping digitalocean.com
ping: digitalocean.com: Temporary failure in name resolution

>  ocker pull helloworld
Using default tag: latest
Error response from daemon: Get https://registry-1.docker.io/v2/: dial tcp: lookup registry-1.docker.io on [::1]:53: read udp [::1]:40123->[::1]:53: read: connection refused

>  apt update
Err:1 http://security.ubuntu.com/ubuntu focal-security InRelease
  Temporary failure resolving 'security.ubuntu.com'
Err:2 https://repos-droplet.digitalocean.com/apt/droplet-agent main InRelease
  Temporary failure resolving 'repos-droplet.digitalocean.com'
Err:3 https://download.docker.com/linux/ubuntu focal InRelease
  Temporary failure resolving 'download.docker.com'
Err:4 http://mirrors.digitalocean.com/ubuntu focal InRelease
  Temporary failure resolving 'mirrors.digitalocean.com'
Err:5 http://mirrors.digitalocean.com/ubuntu focal-updates InRelease
  Temporary failure resolving 'mirrors.digitalocean.com'
Err:6 http://mirrors.digitalocean.com/ubuntu focal-backports InRelease
  Temporary failure resolving 'mirrors.digitalocean.com'
Reading package lists... Done
Building dependency tree       
Reading state information... Done
All packages are up to date.
W: Failed to fetch http://mirrors.digitalocean.com/ubuntu/dists/focal/InRelease  Temporary failure resolving 'mirrors.digitalocean.com'
W: Failed to fetch http://mirrors.digitalocean.com/ubuntu/dists/focal-updates/InRelease  Temporary failure resolving 'mirrors.digitalocean.com'
W: Failed to fetch http://mirrors.digitalocean.com/ubuntu/dists/focal-backports/InRelease  Temporary failure resolving 'mirrors.digitalocean.com'
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/focal-security/InRelease  Temporary failure resolving 'security.ubuntu.com'
W: Failed to fetch https://download.docker.com/linux/ubuntu/dists/focal/InRelease  Temporary failure resolving 'download.docker.com'
W: Failed to fetch https://repos-droplet.digitalocean.com/apt/droplet-agent/dists/main/InRelease  Temporary failure resolving 'repos-droplet.digitalocean.com'
W: Some index files failed to download. They have been ignored, or old ones used instead.

I HAVE added 2 more nameservers, 1.1.1.1 and 8.8.8.8, which I can ping. By this I mean:

> vim etc/netplan/50-cloud-init.yaml

network:
    version: 2
    ethernets:
        eth0:
            addresses:
            - 143.110.178.152/20
            - 10.47.0.5/16
            gateway4: 192.75.31.155

            match:
                macaddress: 0a:ee:7a:c3:93:aa
            nameservers:
                addresses:
                - HERE I"VE ADDED 4 8s, line below, 4 1s
                - 67.207.67.2
                - 67.207.67.3
                search: []
            set-name: eth0

It did not help. I have modified /etc/hosts to add IP for docker registry. This yielded invalid cert message:

>  docker pull helloworld
Using default tag: latest
Error response from daemon: Get https://registry-1.docker.io/v2/: x509: certificate is valid for *.setupdev.abaris.com.br, *.abaris.com.br, not registry-1.docker.io

Ideas are more than welcome. I’m now looking into firewall config, but I have not changed it or dabbled in it, so I’m not particularly hopeful. Also, Networking tab in config panel indicated it’s not a good lead.