Hmm, I don't know enough to give you a confident answer yet. The knowledge sources provided do not contain specific step-by-step instructions for setting up Ory Keto with a PostgreSQL database using Docker Compose and Keto YAML files. However, you can refer to the [Ory documentation](https://www.ory.sh/docs/) for more detailed instructions.

I'm sorry, but the knowledge sources provided do not contain specific information or troubleshooting steps for connection issues when setting up Ory Keto with a PostgreSQL database using Docker Compose and Keto YAML files. However, here are some general tips that might help: 1. Ensure that the PostgreSQL service is running and accessible. 2. Verify that the DSN (Data Source Name) is correctly configured in your

keto.yml

file. It should point to your PostgreSQL instance. 3. Check the logs of the Keto and PostgreSQL containers for any error messages. This can often provide clues about what's going wrong. 4. Make sure that the PostgreSQL container and the Keto container are in the same Docker network, or are otherwise able to reach each other. For more specific assistance, you might want to consider reaching out to the Ory community or seeking [professional support](https://www.ory.sh/support/) from Ory.