Windows，C++:一个服务器套接字上有两个连接

我不知道这是一个一般的网络问题还是一个简单的编程问题，所以我决定把它发布在这里。

在尝试制作聊天程序时，我遇到了以下情况：
-我启动了服务器程序；服务器在端口22001上创建一个套接字；服务器等待连接(accept()挂起)
-我启动客户端程序；客户端连接无错误；客户端发送无误
-服务器接收消息
然后：
-我在同一端口上启动另一个客户端(客户端程序的另一个实例，而不停止或断开第一个客户端的连接)
-第二个客户端连接时没有出现错误(？！)，尽管服务器不再处于"accept()pending"状态
-第二个客户端发送消息时没有显示任何错误(？！)
-服务器不接收来自第二个客户端的消息(？！)
实验的最后一步：
-我断开服务器端的套接字；此时，两个(？！)客户端在发送时都显示错误。

服务器和客户端在同一台机器上运行，并配置为使用端口22001和机器的ip(比如192.168.123.123)。
我使用带读写超时的阻塞套接字，并使用select()使accept()超时。我使用SO_REUSEADDR。我承认我并不完全知道select()是如何工作的
我知道tcp/ip决定了基于集合的连接之间的差异：服务器ip、服务器端口、客户端ip客户端端口。在我的情况下，客户端端口应该不同，而且它们似乎是不同的。但是52428(？！)是什么端口？为什么三个端口都相同(请参阅下面的日志)？远程端口通过getpeername()获取，本地端口通过getsockname()获取
我认为在同一端口的服务器上有多个连接是可能的，但不在同一套接字上。我错了吗
请注意，在服务器断开连接后，客户端1显示错误10053，而客户端2显示错误10054。
那么，这一切是怎么可能的呢？如何在服务器上防止同一套接字上的多个连接，但允许同一端口上的多条连接？

程序的输出如下：

Server:
1) Skt 0: SocketListen 116 created - Port 22001 IP 192.168.123.123.
2) Skt 0: Wait for client connection/
3) Skt 0: SocketAccept 120 created.
4) Skt 0: Remote port is 52428 (SocketListen).
5) Skt 0: Remote port is 52428 (SocketAccept).
6) Skt 0: Local  port is 22001 (SocketListen).
7) Skt 0: Local  port is 22001 (SocketAccept).
8) Skt 0: Client connected.
9) Skt 0: InUse.
10) Skt 0: << Src=Cli1= Dst=Cli2= Body=Text_A_0.
11) Skt 0: << Src=Cli1= Dst=Cli2= Body=Text_B_0.
12) Skt 0: closing...
13) Skt 0: Both sockets (Listen and Accept/Connect) droped.
14) Skt 0: closed.
Client 1:
1) Socket 116 created.
2) Socket connected - Port 22001 IP 192.168.123.123.
3) Remote port is 52428.
4) Local  port is 62193
5) Sent  to  Cli2 CliString: =Text_A_0=.
6) Sent  to  Cli2 CliString: =Text_B_0=.
7) ERROR !!! Port 22001 cannot be reached. Error =10053.
8) ERROR !!! setsockopt( recv_timeout ) failed.
9) Socket closed.
Client 2:
1) Socket 116 created.
2) Socket connected - Port 22001 IP 192.168.123.123.
3) Remote port is 52428.
4) Local  port is 62194
5) Sent  to  Cli1 CliString: =Text_C_0=.
6) Sent  to  Cli1 CliString: =Text_D_0=.
7) ERROR !!! Port 22001 cannot be reached. Error =10054.
8) ERROR !!! setsockopt( recv_timeout ) failed.
9) Socket closed.

服务器，部分代码：

class SktSvr
{
uint32 u32SktIdx;
uint16 u16PortNr;
string strIpAddr;
WSADATA wsaData;
struct sockaddr_in sAddr_Svr;
SOCKET SktListen, SktAccept;
int iRes;
thread * pThreadRecv, * pThreadSend;
mutex Mutex_CliId;
static mutex Mutex_MailBoxes;
static map< string, map< string, string > > MailBoxes; // key = destin , key = source, message
public:
char achCliId[ MSG_SRC_STR_LEN + 1 ];
bool bIsPrep;
atomic<bool> bInUse;
SktSvr( uint32 u32SktIdx_p, uint16 u16PortNr_p, char * pchAddr_p = "127.0.0.1" )
{
u16PortNr = u16PortNr_p;
strIpAddr = pchAddr_p;
u32SktIdx = u32SktIdx_p;
bIsPrep = bInUse = false;
pThreadRecv = pThreadSend = NULL;
achCliId[ 0 ] = '';
memset( &sAddr_Svr, 0, sizeof( sAddr_Svr ) );
sAddr_Svr.sin_family = AF_INET; // server byte order
wstring wstrIpAddr( strIpAddr.begin(), strIpAddr.end() );
InetPton( AF_INET, wstrIpAddr.c_str(), &sAddr_Svr.sin_addr.s_addr ); //INADDR_ANY; // host addr
sAddr_Svr.sin_port = htons( u16PortNr );
char chOptVal = 1;
if( ( iRes = WSAStartup( MAKEWORD( 2, 2 ), &wsaData ) ) != NO_ERROR )
{
printf( "nSkt %d: ERROR !!! WSAStartup failed: %d.", u32SktIdx, iRes );
}
else if( ( SktListen = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP ) ) == INVALID_SOCKET ) // default protocol
{
printf( "nSkt %d: ERROR !!! Port %d can not be opened.", u32SktIdx, u16PortNr );
printf( "nSkt %d: Error =%ld.", u32SktIdx, WSAGetLastError() );
WSACleanup();
}
else if( setsockopt( SktListen, SOL_SOCKET, SO_REUSEADDR, &chOptVal, sizeof( chOptVal ) ) == -1 )
{
printf( "nSkt %d: ERROR !!! Port %d set options failed.", u32SktIdx, u16PortNr );
printf( "nSkt %d: Error =%ld.", u32SktIdx, WSAGetLastError() );
WSACleanup();
}
else if( bind( SktListen, ( struct sockaddr * ) &sAddr_Svr, sizeof( sAddr_Svr ) ) == SOCKET_ERROR )
{
printf( "nSkt %d: ERROR !!! Port %d can not be bound.", u32SktIdx, u16PortNr );
printf( "nSkt %d: Error =%ld.", u32SktIdx, WSAGetLastError() );
WSACleanup();
}
else if( listen( SktListen, 5 ) == SOCKET_ERROR ) // size for backlog queue = 5
{
printf( "nSkt %d: ERROR !!! Port %d can not listen.", u32SktIdx, u16PortNr );
printf( "nSkt %d: Error =%ld.", u32SktIdx, WSAGetLastError() );
WSACleanup();
}
else
{
printf( "nSkt %d: SocketListen %d created - Port %d IP %s.",
u32SktIdx, SktListen, u16PortNr, strIpAddr.c_str() );
bIsPrep = true;
}
}
bool SktConn()
{
int iRes;
struct timeval tmvl;
fd_set rfds;
FD_ZERO( &rfds );
FD_SET( SktListen, &rfds );
tmvl.tv_sec = TIMEOUT_SKT_CONN_S;
tmvl.tv_usec = 0;
if( 0 ) {}
else if( 1 && ( iRes = select( SktListen + 1, &rfds, (fd_set*)0, (fd_set*)0, &tmvl ) ) <= 0 )
{
// connect timeout
//printf( "nSkt %d: Socket Connect timeout.", u32SktIdx );
bInUse = false;
}
else if( ! FD_ISSET( SktListen, &rfds ) )
{
printf( "nSkt %d: Selected another.", u32SktIdx );
}
else if( ( SktAccept = accept( SktListen, NULL, NULL ) ) == INVALID_SOCKET )
{    printf( "nSkt %d: ERROR !!! Port %d did not connect.", u32SktIdx, u16PortNr );
printf( "nSkt %d: Error =%ld.", u32SktIdx, WSAGetLastError() );
bInUse = false;
}
else
{
printf( "nSkt %d: SocketAccept %d created.", u32SktIdx, SktAccept );
struct sockaddr_in sAddr;
socklen_t len;
getpeername( SktListen, ( struct sockaddr* )&sAddr, &len );
printf( "nSkt %d: Remote port is %d (SocketListen).", u32SktIdx, ntohs( sAddr.sin_port ) );
getpeername( SktAccept, ( struct sockaddr* )&sAddr, &len );
printf( "nSkt %d: Remote port is %d (SocketAccept).", u32SktIdx, ntohs( sAddr.sin_port ) );
int iAddrLen = sizeof( sAddr );
if( getsockname( SktListen, ( struct sockaddr * )&sAddr, &iAddrLen ) == 0 &&
sAddr.sin_family == AF_INET && iAddrLen == sizeof( sAddr ) )
printf( "nSkt %d: Local  port is %d (SocketListen).", u32SktIdx, ntohs( sAddr.sin_port ) );
if( getsockname( SktAccept, ( struct sockaddr * )&sAddr, &iAddrLen ) == 0 &&
sAddr.sin_family == AF_INET && iAddrLen == sizeof( sAddr ) )
printf( "nSkt %d: Local  port is %d (SocketAccept).", u32SktIdx, ntohs( sAddr.sin_port ) );
bInUse = true;
}
return bInUse;
}