Marked as helpful by the asker
Two things in that line:
'localhost'means only processes inside the container can reach it. Render's router is outside, so it sees nothing. Bind to all interfaces.- Render tells you which port to use via
PORT. Read it instead of hardcoding.
const port = process.env.PORT || 3000;
app.listen(port, '0.0.0.0', () => console.log(`Listening on ${port}`));Then remove the PORT you set manually, let Render inject it.
deployed, live. chatgpt wrote 'localhost' in every example it gave me 
rocco
rocco Same issue with uvicorn defaulting to 127.0.0.1, for the Python folks. 
grace_mw
grace_mw Same root cause on Railway and Fly, for anyone searching. anjali_p
