Composer build failures due to DNS error

My builds fail for over a week already with the following error:

The “https://packages.drupal.org/7/drupal/provider-2008-3%247eb49f16d9ece9e2688a4820645807d52ef216ba8849b8c9b590547de235f885.json” file could not be downloaded: failed to open stream: Operation timed out
Retrying with degraded mode, check Troubleshooting - Composer for more info

[Composer\Downloader\TransportException]
The “http://repo.packagist.org/p/provider-2013%240078c6e2ea8258569f076a069de5636241177466c3ecf957b246601a3ea07bf7.json” file could not be downloaded: php_network_getaddresses: getaddrinfo failed: Name does not resolve
failed to open stream: php_network_getaddresses: getaddrinfo failed: Name does not resolve

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