Can not catch over >1000 message when server send over 1000 message at a time nodejs udp

I write application to send file multicast by nodejs I read file by chunk and send it in block like this

for (var block = 1; block <= number_of_block; block++) {
                   sendBlock(FILEPATH, block)

function sendBlock by CHUNK

function sendBlock(file, block) {
           fs.open(file, 'r', function(err, fp) {
            if (err) {            
                return;
            }
            var buf = new Buffer(4 + CHUNK_SIZE);
            fs.read(fp, buf, 4, CHUNK_SIZE, (block - 1) * CHUNK_SIZE, function(err, bytesRead) {
                if (err) {

                }
                buf[0] = 0;
                buf[1] = opcodes.OPCODE_DATA;
                buf[2] = (block >> 8) & 0xFF;
                buf[3] = block & 0xFF;
                udpserver.send(buf, 0, 4 + bytesRead, PORT, MULTICAST_IP_ADDRESS);
                fs.close(fp);
            });
        });

I create client to receive message

fs.open(fileName, 'a', function(e, id) {
                if (4 + CHUNK_SIZE > message.length) {
                    fs.write(fd, message, 4, message.length - 4, (block - 1) * CHUNK_SIZE, function() {
                        fs.close(fd, function() {
                            console.log('file closed', block);
                            send("miss block:" + missArray);
                        });
                    });
                } else {
                    console.log("message length:", message.length)
                    console.log((block - 1) * CHUNK_SIZE)

                    fs.write(fd, message, 4, CHUNK_SIZE, (block - 1) * CHUNK_SIZE, function() {
                        fs.close(fd, function() {
                            console.log('1file closed', block);
                            if (block % NUMBER_BLOCK == 0) {
                                if (blockArray.length > 0) {
                                    missArray = missArray.concat(blockArray);
                                }
                                blockArray = range(block + 1, NUMBER_BLOCK)
                            }

                            //udpserver.send(block+1)
                        });
                    });
                }
            });

But when server send over 1000 message client can not catch it all server send

block -- 6907
block -- 6908
block -- 6909
block -- 6910
block -- 6911
block -- 6912
block -- 6913

client reveive and write

block ------  1008
block ------  1009
block ------  1010
block ------  1011

And I test the maximum file to receive is 10.4 MB.

How to receive all data from sender?