Enable TCP Keep-Alive in your NestJS microservice by creating a custom socket class that configures the connection to stay active. This prevents AWS NLB timeouts caused by inactivity ( I have this problem with docker swarm ideal network connection ).

import { JsonSocket } from '@nestjs/microservices/helpers';
import { Socket } from 'net';

class CustomTcpSocket extends JsonSocket {
  constructor(socket: Socket) {
    socket.setKeepAlive(true, 10000); // Enable Keep-Alive with a 10s 

    super(socket);
  }
}
app.connectMicroservice<MicroserviceOptions>({
  transport: Transport.TCP,
  options: {
    host: '0.0.0.0',
    port: tcpPort, // Replace with your port
    socketClass: CustomTcpSocket,
  },
});