Hi Railway folks. I’m stuck with a persistent “Application failed to respond / 502 Bad Gateway” on a Next.js service inside a monorepo.

Repo layout (monorepo):

• frontend/ = Next.js 14 app (should be the only thing running in this service)
• root also has FastAPI, but this Railway service is configured to use only frontend/.

Railway service config:

• Root Directory:frontend
• Custom Build Command:npm ci && npm run build
• Custom Start Command:node .next/standalone/server.js
• Build finishes OK, logs show standalone build + copy step ran.
• Public domain assigned only to this service.
• Domain networking shows target port 8080 (Railway UI says setup complete).

What I changed to align standalone mode:

1. frontend/next.config.js uses output: "standalone".
2. frontend/package.json:
   • "build": "next build && npm run copy-static"
   • "copy-static": "cp -r .next/static .next/standalone/.next/ && cp -r public .next/standalone/ 2>/dev/null || true"
   • "start": "node .next/standalone/server.js"
3. frontend/Procfile: web: node .next/standalone/server.js
4. frontend/nixpacks.toml start also node .next/standalone/server.js

Current behavior:

• Deploy completes, but the service never responds; any request gives 502 and Railway overlay says “Application failed to respond.”
• This happens both on the custom domain and on the Railway default domain.

Question:

Given a Next.js standalone app running with node .next/standalone/server.js and Root Directory set to frontend/, what else commonly causes Railway’s edge proxy to fail connecting?

Should I remove Procfile, change target port, or explicitly bind host/port somewhere for standalone?

Any specific log line or setting I should check next?

Thanks