ESP8266 send to server

#include <Arduino.h>
#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>

const char* ssid = "nhtcntt";
const char* pass = "123456789";
String URL = "http://192.168.123.1:80/update";

void SendInfo2Server(float Nhietdo, float DoAm);

void setup() {
    Serial.begin(115200);
    Serial.print("Connectting to");
    Serial.println(ssid);
    WiFi.mode(WIFI_STA);
    WiFi.begin(ssid, pass);
    while( WiFi.status() != WL_CONNECTED)
    {
        delay(2000);
        Serial.println("Failed - Try connect");
    }
    Serial.println("WiFi connected");
    Serial.print("IP address: ");
    Serial.println(WiFi.localIP());
    Serial.print("MAC: ");
    Serial.println(WiFi.macAddress());

}

void loop()
{
    SendInfo2Server(10.20, 10.10);

}

/*
 URL: http://IPorName:80/update
 method: POST
 http header:
             User-Agent: MAC Address
             Content-Type: application/json
             Content-Length: length(http body)
             Connection: close
 http body:
             {
                 "nhietdo" : float,
                 "doam"    : float
             }
*/

void SendInfo2Server(float Nhietdo, float DoAm)
{
    HTTPClient http;
    http.begin(URL);
    http.addHeader("Content-Type", "application/json");
    http.setUserAgent(WiFi.macAddress());
    int statuscode = http.POST("{\"nhietdo\" : " + String(Nhietdo) + ", \"doam\" : \"" + String(DoAm) + "%\"}");
    if(statuscode > 0)
    {
        String payload = http.getString();
        Serial.print("payload: ");
        Serial.println(payload);
    }
    http.end();
    delay(5000);
}