User reports persistent 503 errors between private Docker Spaces on Hugging Face

A user is experiencing a persistent HTTP 503 Service Temporarily Unavailable error when attempting to communicate between multiple private Docker Spaces deployed on Hugging Face. The application architecture consists of a main backend sending requests to five worker Spaces, which function correctly in local Docker environments but fail upon deployment.

• The main backend sends HTTP requests to worker URLs, but every request returns a 503 error.
• Worker logs indicate successful application startup and model loading, but never log incoming POST requests.
• The user verified that the Dockerfile, port 7860 configuration, environment variables, and authentication are correct.
• Health endpoints are accessible, and all Spaces appear as Running in the Hugging Face dashboard.
• Redeploying with new Spaces did not resolve the issue, suggesting a platform-level routing or ingress problem.