Update gives error message 'check internet connection' ,[[

ATTENTION PALLEBONE
Using 20.04 I get the same error message as with 19.10. Adding balenaEtcher required adding DNS 8.8.8.8 then it worked 100%.
sudo apt-get update this morning returned

ray@rayLinux2020:~$ sudo apt-get update
[sudo] password for ray:
Ign:1 http://za.archive.ubuntu.com/ubuntu focal InRelease
Ign:2 http://za.archive.ubuntu.com/ubuntu focal-updates InRelease
Hit:3 http://ppa.launchpad.net/heyarje/makemkv-beta/ubuntu focal InRelease
Ign:4 http://za.archive.ubuntu.com/ubuntu focal-backports InRelease
Hit:5 http://security.ubuntu.com/ubuntu focal-security InRelease
Err:6 http://za.archive.ubuntu.com/ubuntu focal Release
404 Not Found [IP: 197.155.77.2 80]
Hit:7 https://repo.skype.com/deb stable InRelease
Err:8 http://za.archive.ubuntu.com/ubuntu focal-updates Release
404 Not Found [IP: 197.155.77.2 80]
Err:10 http://za.archive.ubuntu.com/ubuntu focal-backports Release
404 Not Found [IP: 197.155.77.2 80]
Hit:11 http://ppa.launchpad.net/lah7/ubuntu-mate-colours/ubuntu focal InRelease
Ign:9 https://dl.bintray.com/etcher/debian stable InRelease
Get:12 https://dl.bintray.com/etcher/debian stable Release [3,674 B]
Reading package lists... Done
E: The repository 'http://za.archive.ubuntu.com/ubuntu focal Release' no longer has a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: The repository 'http://za.archive.ubuntu.com/ubuntu focal-updates Release' no longer has a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: The repository 'http://za.archive.ubuntu.com/ubuntu focal-backports Release' no longer has a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

The missing release file may be unrelated to the Etcher problem?