MPI_Send/MPI_Recv blocked using MPI_Comm_connect / MPI_Comm_accept - c

Question

I'm developing a client/server application by using MPI. I'm using MPI_Open_port(), MPI_Comm_Accept() and MPI_Comm_connect() for doing that. Inside the application I also use MPI_Send() and MPI_Recv() for the client/server comms.
All is fine when I transfer small arrays by using MPI_Send()/MPI_Recv(). I have a problem when some array growth in size. For some reason for large arrays MPI_Send/Recv functions are blocking the execution. It is like I'm sending and receiving the data on the the same Rank, what is true, but I'm using different communicators. I really don't understand why it doesn't work.
For a size 16*16*16 all works fine but, for instance, for a size equal to 32*32*32 it doesn't. I really want to know what is happening and I'll appreciate any advice for solving this issue.
Thanks.
The server is:
#include<mpi.h>
#include<stdio.h>
#define SIZE 32*32*32
//#define SIZE 16*16*16
int main(int argc, char *argv[])
{
MPI_Comm client;
char port_name[MPI_MAX_PORT_NAME];
FILE* port_file;
int buf[SIZE];
MPI_Init(&argc,&argv);
port_file = fopen("ports.txt","w");
MPI_Open_port(MPI_INFO_NULL, port_name);
fprintf(port_file,"%s\n",port_name);
fclose(port_file);
MPI_Comm_accept(port_name, MPI_INFO_NULL, 0, MPI_COMM_WORLD, &client);
printf("Client connected...\n");
printf("Sending data...\n");
MPI_Send((void*)&buf, SIZE, MPI_INT, 0, 0, client);
printf("Data sent...\n");
MPI_Comm_free(&client);
MPI_Close_port(port_name);
MPI_Finalize();
return 0;
}
The client is:
#include<mpi.h>
#include<stdio.h>
#define SIZE 32*32*32
//#define SIZE 16*16*16
int main(int argc, char *argv[])
{
MPI_Comm server;
char port_name[MPI_MAX_PORT_NAME];
FILE* port_file;
int buf[SIZE];
MPI_Init(&argc,&argv);
port_file = fopen("ports.txt","r");
fscanf(port_file,"%s\n",port_name);
fclose(port_file);
MPI_Comm_connect(port_name, MPI_INFO_NULL, 0, MPI_COMM_WORLD, &server);
printf("Client connected...\n");
printf("Receiving data...\n");
MPI_Recv((void*)&buf, SIZE, MPI_INT, MPI_ANY_SOURCE,
MPI_ANY_TAG, server, MPI_STATUS_IGNORE);
printf("Data received...\n");
//MPI_Comm_disconnect(&server);
MPI_Finalize();
return 0;
}