consideration to speedup tcp/udp connection - c++

Question

I'm using winsock2 library to write a SDK(Software Developement Kit) for a digital board with 1Gbps ethernet on it. the problem I'm facing is that I can not get enough transfer rate(TX/RX) through ethernet uing TCP/UDP. i rather use UDP-RX as a case study to understand each parameter than can speed up my connection. with the code below i can send data from my PC to my device in just ~350 Mbps.
Start Listening:
//Initialize winsock library
if (WSAStartup(MAKEWORD(2, 2), &m_wsa) != 0)
{
error = WSAGetLastError();
}
//Create a socket
if ((m_serversocket = socket(AF_INET, SOCK_DGRAM, 0)) == INVALID_SOCKET)
{
error = WSAGetLastError();
WSACleanup();
return;
}
int buffersize = 0x200000;
int buffersizelen = sizeof(buffersize);
setsockopt(m_serversocket, SOL_SOCKET, SO_RCVBUF, (char*)&buffersize, buffersizelen);
//Prepare the sockaddr_in structure
memset(&m_serveraddress, 0, sizeof(m_serveraddress));
m_serveraddress.sin_family = AF_INET;
inet_pton(AF_INET, SERVER_Address, &m_serveraddress.sin_addr.s_addr);
m_serveraddress.sin_port = htons(SEND_PORT_number);
// Bind the socket to any address and the specified port.
if (bind(m_serversocket, (struct sockaddr *)&m_serveraddress, sizeof(m_serveraddress)) == SOCKET_ERROR)
{
error = WSAGetLastError();
return;
}
Sending file:
sendchunk = 1000;
// Read File and fill the buffer
if ((m_err = fopen_s(&m_send_file, m_send_filename.toLocal8Bit().data(), "rb")) == 0)
{
// start to send buffer
while (!(feof(m_send_file) || m_stopsend))
{
remainsize = fread(read_data, 1, sendfilesize / count, m_send_file);
sndsize_ProgBar += remainsize;
sentsize = 0;
timer.start();
while ((remainsize >= sendchunk) && !(m_stopsend))
{
sendto(m_serversocket, read_data + sentsize, sendchunk, 0, (struct sockaddr *)&m_serveraddress, addrlengh); // 1024
sentsize += sendchunk;
remainsize -= sendchunk;
}
elapsedtimemicrosec = timer.getElapsedTimeInMicroSec();
timer.stop();
rcvRate = (float)(((remainsize + sentsize)) / elapsedtimemicrosec);
emit UpdateSendRate(rcvRate);
}
}
any suggestion to speedup connection?
P.S: i already tried different sendchunk and choose the best.