clean and reuse open port. winsock c++ - c++

Question

I am working on a client-server application where I have two different ports, one (principal) for us send and receive messages or any other order, and another one to send and receive screenshots of the server to the client. From client to server notice to start us send'll catch and showing in a new window ... works fine but if I close the window and open it again then and I can not connect to that port (bind fails me).
MY question is how do I clean or completely release the port I use for screenshots without affecting the main port, that is, when you close the window to release the port as if I had never used and advise the client to do the same.
Here I leave the code:
Server:
int serviceCapture(int port)
{
int error;
WSAData wsaDataER;
error = WSAStartup(MAKEWORD(2, 2), &wsaDataER);
if (error == SOCKET_ERROR)
{
return 1;
}
// ShowMessage ("Server: WinSocket Started Correctly!\n");
sock_ER = socket(AF_INET, SOCK_STREAM, 0);
if (sock_ER == SOCKET_ERROR)
{
return 2;
}
struct sockaddr_in escritorioRem; // New! Our network socket structure
escritorioRem.sin_family = AF_INET; // Always have ti as this for internet
escritorioRem.sin_port = htons(puerto); // Dont forget the byte ordering
escritorioRem.sin_addr.s_addr = INADDR_ANY;internet
if(!enviandoCapturas){
error = bind(sock_ER, (sockaddr*)&escritorioRem, sizeof(escritorioRem)); // Attempt to bind the socket
if (error == SOCKET_ERROR)
{
return 3 ;
}
}
error = listen(sock_ER, 1); // Listen for connections
if (error == SOCKET_ERROR)
{
return 4;
}
// }
//ShowMessage ( "Server: Waiting for a client to connect ...\n"); // Just to keep us up to date - ish
int len= sizeof (struct sockaddr);
sock_ER=accept(sock_ER,(sockaddr*)&escritorioRem, &len);
//
//do{
if( sock_ER<0){
return 5;
}
sendingCaps=true;
startSendCaps();
return 0;
}
Client:
int client(string serv, int puerto)
{
int error;
WSAData wsaData;
error = WSAStartup(MAKEWORD(2, 2), &wsaData);
if (error == SOCKET_ERROR)
{
return 1;
}
// ShowMessage( "Client: WinSocket Loaded.\n");
if (sock == SOCKET_ERROR)
{
return 2;
}
// ShowMessage( "Client: Socket Opened Successfully!\n");
const char *server_name = serv.c_str(); // The server name we will connect to
struct hostent *host_entry; // Translates into something the computer can understand
host_entry = gethostbyname(server_name); // Gather out information
if (host_entry == NULL)
{
return 3;
}
struct sockaddr_in server;
server.sin_family = AF_INET;
server.sin_port = htons((unsigned short) puerto);
server.sin_addr.s_addr = *(unsigned long*) host_entry->h_addr;
if(connect(ventanaCliente->sock, (sockaddr*)&server, sizeof(struct sockaddr))<0){
return 4;
}
receivingCaps=true;
strartReceiveCaps();
return 0;
}