Issue Summary

Unable to connect to PostgreSQL database using internal network (postgres.railway.internal:5432) during application deployment and runtime. Public database URL works correctly, but internal connection consistently fails.

Error Details

Error Message:

Error: P1001: Can't reach database server at `postgres.railway.internal:5432`
Please make sure your database server is running at `postgres.railway.internal:5432`.

When it occurs:

• During build process when running npx prisma migrate deploy
• At application startup when attempting database operations
• Consistently fails with internal URL, works with public URL

Environment Information

Project Setup:

• Project Name: chaos-whisper
• Services:
  • Next.js application (chaos-whisper)
  • PostgreSQL database (Postgres)
• Both services are in the same Railway project
• Database service status: Active (green checkmark)
• Application deployment method: GitHub integration

Database Configuration:

• PostgreSQL service is running normally (verified via Railway dashboard)
• Database can be accessed via DATABASE_PUBLIC_URL
• Database cannot be accessed via DATABASE_URL (internal)
• Railway dashboard shows "You have no tables" because migrations fail

What I've Tried

1. Verified Environment Variables:
   • Confirmed DATABASE_URL is set as variable reference: ${{Postgres.DATABASE_URL}}
   • Double-checked connection string format
   • Verified credentials match between public and internal URLs
2. Tested Connection Methods:
   • DATABASE_PUBLIC_URL: Works perfectly
   • DATABASE_URL (internal): Connection timeout
   • Database service health: Normal operation
3. Deployment Strategy Changes:
   • Moved database operations from build time to runtime
   • Added connection retry logic
   • Attempted different timing approaches
4. Network Diagnostics:
   • Confirmed both services are in same project
   • No custom network isolation configured
   • DNS resolution for postgres.railway.internal appears to fail

Expected Behavior

The application should be able to connect to PostgreSQL using the internal network URL (postgres.railway.internal:5432) for:

• Database migrations during deployment
• Runtime database operations
• Better performance and security compared to public URL

Current Workaround

Using DATABASE_PUBLIC_URL as a temporary solution, but this is not ideal for production due to:

• Higher latency through public internet
• Security implications
• Not following Railway best practices

Request

Please investigate why the internal database connection is failing and help restore proper internal network connectivity between my Next.js application and PostgreSQL service.

Additional Information

Connection String Format (sanitized):

Internal (failing): postgresql://postgres:***@postgres.railway.internal:5432/railway
Public (working):   postgresql://postgres:***@[public-host]:5432/railway

Application Stack:

• Next.js 15.3.5
• Prisma 6.11.1
• PostgreSQL (Railway managed)

Thank you for your assistance in resolving this internal networking issue.