Can't receive messages in ZeroMQ push/pull on Kubernetes

I have read the other questions and I have found no answer...

I have three services deployed in kubernetes: one service that sends messages, one broker and one consumer. The broker and the consumer connect perfectly, but the sender and the broker don't connect.

My sender is in C#, using the NetMQ library, and my broker and my consumer are in Node, using the zeromq library.

My sender binds like this:

public sealed class ZeroMQProvider : IZeroMQProvider, IDisposable{    private readonly PushSocket _socket;    private readonly ILogger<ZeroMQProvider> _logger;    private readonly TimeSpan _sendTimeout;    public ZeroMQProvider(IConfiguration configuration, ILogger<ZeroMQProvider> logger)    {        _socket = new PushSocket($"@tcp://{configuration["ZEROMQ_HOST"]}:{configuration["ZEROMQ_PORT"]}");        _logger = logger;        _sendTimeout = TimeSpan.FromMilliseconds(Convert.ToInt32(configuration["ZEROMQ_TIMEOUT_MS"]));    }    public void Dispose()    {        _socket.Dispose();    }    public Result SendMessage(string message)    {        try        {            bool success = _socket.TrySendFrame(timeout: _sendTimeout, message: message);            if (!success)            {                return Result.Fail(new BrokerError());            }            return Result.Ok();        }        catch (Exception ex)        {            _logger.LogError("{Msg}", ex.Message);            _logger.LogError("{Strace}", ex.StackTrace);            return Result.Fail(new BrokerError());        }    }}

My broker connects like this:

var checkerSocket = new zmq.Pull({connectTimeout: 2000});  try {    checkerSocket.events.on('connect:retry', e => {      console.log(new Date(), e.type);    });    console.log(`BIND: tcp://${config.zeromq.checker.CHECKER_HOST}:${config.zeromq.checker.CHECKER_PORT}`);    checkerSocket.connect(`tcp://${config.zeromq.checker.CHECKER_HOST}:${config.zeromq.checker.CHECKER_PORT}`);

Note that this works in docker-compose but not in Kubernetes, but the addresses are well set and all. The TCP socket is in SYN_SEND state and won't move from there. I have also tried to reverse the roles, but it also works on docker-compose but not in Kubernetes in AWS.

Any ideas?