How to access OpenStack instances from the bastion node when deploying OpenStack using Kolla-Ansible

In test environments, some users choose to build their infrastructure inside KVM virtual machines, while others use cloud instances such as EC2 bare-metal that support nested virtualization. After deploying OpenStack, many of them face a major issue: they are unable to access their OpenStack instances. I encountered the same problem myself. After several weeks of intensive troubleshooting, I eventually found a solution. That is why I would like to share this solution with others who face the same issue, and hopefully contribute to the OpenStack community by providing recommendations that could be added to the official OpenStack documentation.