Udp sender can send but receiver can not receive

Development Programming & Scripting C++
, , ,
1

when i use multicast data with udp ,i can send data but can not receive ！ Please tell me what’s wrong？
void AUdpActor::StartUdp()
{

//send socket
FIPv4Endpoint EndPoint1(FIPv4Address(231, 255, 255, 255), port);
RemoteAddr = EndPoint1.ToInternetAddr();


UdpSenderSocket = FUdpSocketBuilder(TEXT("UpdSendSocket"))
	.AsReusable()
	.WithBroadcast()
	.WithSendBufferSize(2 * 1024 * 1024)
	.WithReceiveBufferSize(2 * 1024 * 1024);
	
if (UdpSenderSocket)
{
	isStartUdpSucessful = true;
	GLog->Logf(TEXT("Send socket create succesful"));
}

//receiver socket

FIPv4Endpoint EndPoint2(FIPv4Address::Any, port);
UdpReceiverSocket = FUdpSocketBuilder(TEXT("UpdReceiverSocket"))
	.AsNonBlocking()
	.AsReusable()
	.BoundToEndpoint(EndPoint2)
	.WithMulticastLoopback()
	.WithReceiveBufferSize(2 * 1024 * 1024);
if (UdpReceiverSocket)
{
	GLog->Logf(TEXT("Receiver socket create succesful"));
	FTimespan ThreadWaitTime = FTimespan::FromMilliseconds(100);
	UdpReceiver = new FUdpSocketReceiver(UdpReceiverSocket, ThreadWaitTime, TEXT("Udp Receiver"));
	
	UdpReceiver->OnDataReceived().BindUObject(this, &AUdpActor::RecvData);

	UdpReceiver->Start();
}

}

2

void AUdpActor::RecvData(const FArrayReaderPtr & ArrayReadPrt, const FIPv4Endpoint & EndPt)
{
//FString msg;
GLog->Logf(TEXT(“Receiver msg”));
}

void AUdpActor::SendData(FString str)
{
	if (!isStartUdpSucessful) return;
	int32 sendNum = 0;
	FString serialized = str;
	TCHAR *serializedChar = serialized.GetCharArray().GetData();
	int32 size = FCString::Strlen(serializedChar);
	UdpSenderSocket->SendTo((uint8*)TCHAR_TO_UTF8(serializedChar), size, sendNum,*RemoteAddr);
	if (sendNum <= 0)
	{
		const FString Str = "Socket is valid but the receiver received 0 bytes, make sure it is listening properly!";
		GLog->Logf(TEXT("warning : %s"), *Str);
	}
	else
	{
		GLog->Logf(TEXT("send str : %s"), *str);
	}
}
3

it work ok！change FIPv4Address(231, 255, 255, 255) to FIPv4Address(255, 255, 255, 255)