Overcloud deploy failed on Cannot download repomd.xml

Issue

The deployment command fails with the following error:

 2023-09-02 23:46:51.144197 | 5aaa091-4aaa-a078-fa6b-000000000405 |      FATAL | Install tripleo-validations package | ttl-directornode | error={"changed": false, "msg": "Failed to download metadata for repo 'rhel-9-for-x86_64-appstream-eus-rpms': Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried", "rc": 1, "results": []}