[NOOB QUESTION] Dialling with push pull socket pair gives connection shutdown/refused

[Edward]

I have the following test code which works:

#include <iostream>
#include <nngpp/nngpp.h>
#include <nngpp/protocol/push0.h>
#include <nngpp/protocol/pull0.h>

using namespace std;

int main()
{
  const std::string addr{"ws://127.0.0.1:9999"};
  nng::socket push_socket = nng::push::open();
  nng::socket pull_socket = nng::pull::open();

  pull_socket.listen(addr.data());
  push_socket.dial(addr.data());


  push_socket.send("love yourself?");

  if(auto buffer = pull_socket.recv(); buffer)
    cerr << "mama! the push socket told me to:\n\t" << (const char *) buffer.release() << '\n';

  return 0;
}

I now try to split this code into two programs which are running on the same local area network. The IP address are taken from ip a.

listener:

#include <iostream>
#include <nngpp/nngpp.h>
#include <nngpp/protocol/push0.h>
#include <nngpp/protocol/pull0.h>

using namespace std;

int main()
{
  const std::string addr{"ws://127.0.0.1:9999"};
  nng::socket pull_socket = nng::pull::open();

  pull_socket.listen(addr.data());

  if(auto buffer = pull_socket.recv(); buffer)
    cerr << "mama! the push socket told me to:\n\t" << (const char *) buffer.release() << '\n';

  return 0;
}

dialler:

#include <iostream>
#include "nngpp/nngpp.h"
#include "nngpp/protocol/push0.h"
#include "nngpp/protocol/pull0.h"
#include <string>

using namespace std;

int main()
{
  const std::string addr{"ws://192.168.1.184:9999"};
  nng::socket push_socket = nng::push::open();

  push_socket.dial(addr.data());


  push_socket.send("love yourself?");

  return 0;
}

No matter which order I start the programs in, I get either a 'Connection refused' or a 'Connection shutdown' nng::exception from the dialler and the listener never receives the message. What am I doing wrong?

[Edward]

it works when using 0.0.0.0 instead of 127.0.0.1