LWIP Can't Connect to Remote Server

Hi. My code is raw tcp/ip client application. It can connect local server on my computer frequently but it can't connect to remote server "sometimes (about 2/3 ratio) " . Remote server is working properly, I guarantee by connecting my computer with simple socket application. If I try to execute TCP_WRITE function, return error 13 so connection error.

I think that My device can't get ACK in timeout or I don't know.

How can ı solve this ?

My device is LPC1769. I use changed LPCopen TCP/IP Server App to client version by myself.

I add some code block related with changed from lpcopen example. 

I attach my lwipopt.h, that options can execute webserver application with 70kb webpage very fast.

My pcb is blocked at echo_pcb->state = SYN_Sent. It can't get ACK

void tcp_echoclient_connect(void)
{
struct ip_addr DestIPaddr;

if (echo_pcb != NULL)
{
IP4_ADDR( &DestIPaddr, 192, 168, 1, 39 );

/* connect to destination address/port */
tcp_connect(echo_pcb,&DestIPaddr,7,echo_accept);
}
else
{
/* deallocate the pcb */
memp_free(MEMP_TCP_PCB, echo_pcb);
// DEBUGOUT("\n\r can not create tcp pcb");

}
}

 

 

void
echo_init(void)
{
echo_pcb = tcp_new();
if (echo_pcb != NULL)
{
err_t err;

err = tcp_bind(echo_pcb, IP_ADDR_ANY,7);
if (err == ERR_OK)
{
tcp_echoclient_connect();
}
else
{
/* abort? output diagnostic? */
}
}
else
{
/* abort? output diagnostic? */
}
}

 

 

int Enet_Write(char *str){

 

err_t wr_err = ERR_OK;

while ( (str != NULL) && (strlen(str) <= tcp_sndbuf(echo_pcb)) && strlen(str) < 1025 && echo_pcb != NULL)
{

wr_err = tcp_write(echo_pcb, str, strlen(str) , 1);

if (wr_err == ERR_OK)
{
tcp_output(echo_pcb);
DEBUGOUT("Transmitted data is : %s\r\n", str);
if( echo_pcb->unacked != NULL )
DEBUGOUT("Acknowledged \r\n");

break;
}
else if(wr_err == ERR_MEM)
{
/* we are low on memory, try later / harder, defer to poll */
DEBUGOUT("Tcp_write memory error \r\n");
}
else
{
/* other problem ?? */
DEBUGOUT("wr_err is %d \r\n",wr_err);
}
}

}