Why I can't connect two containers between each other in railway.app?

Question

I have a microservices architecture with 6 containers. One of them is the back (a server in python with asyncio) that is running in the address 0.0.0.0:1234 -> the host is '0.0.0.0' to be public. And I have another microservice in Node JS, it is a socket connector, it has to connect with the back in python that is running in 0.0.0.0:1234, but I can't connect.

Error: errno: -111, code: 'ECONNREFUSED',

Why I can't connect the two containers between each other if it supposed to have a network in common?

I connect the others microservices between each other with the public domain that provides railway, but in this case I need the host and the port to connect it through sockets.

const connectToPythonServer = () => {
    client.connect({
        port: 1234,
        host: '0.0.0.0'
    }, () => {
    // client.connect(1234, '0.0.0.0', () => {
        console.log('Connected al back de python, es decir al sv asincronico');
        client.write('Hello, server! Love, Client.');
    });
}

This is how connect my Node JS connector to the back. It is working locally, but when I took this to railway, it doesn't work. It doesn't connect. **