Socket.io stopped working

I don't know what possibly could have change, but my client/server communication with socket.io stopped working. Here is my server app :

io.sockets.on('connection', (socket) => {
    console.log('user connected');

    consumer.on('message', function (message) {
        console.log(message);
        io.sockets.emit("message",message);
    });
});

The message are printed in the console. The consumer is a Kafka consumer but this shouldn't matter. Here is my client component:

this.connection = this.streamService.getMessages().subscribe((message: string) => { 
        console.log("Receiving message " + message);
}

Here is my client service:

getMessages() { 

    let observable = new Observable(observer => { 
        this.socket = io.connect(this.url);

        this.socket.on('message', (data: any) => {
             console.log(data);
             observer.next(data.value); 
        }); 
        return () => {
             this.socket.disconnect(); 
        }; 
    }) 
    return observable; 
} 

None of my client side log are displayed except "user connected". I get a Get request to http:/localhost:3000/socket.io/ frequently. Both client and server use "socket.io-client": "^2.0.1".

Thank you for your help!

via GrinnS