Arduino HTTP Client not connecting to Firebase - firebase

Question

I am trying to post GPS data to firebase using the Arduino Uno R3, SIM800L and NEO6M via GPRS. I have managed to connect to the APN, but I can't get the "http_client.connect()" to work. It keeps giving the same error.
Code
#define TINY_GSM_MODEM_SIM800
#define TINY_GSM_RX_BUFFER 256
#include <TinyGsmClient.h>
#include <ArduinoHttpClient.h>
#include <TinyGPS++.h>
#include <SoftwareSerial.h>
#define SerialMonitor Serial
#define ARDUINO_GPS_RX 3
#define ARDUINO_GPS_TX 2
TinyGPSPlus tinyGPS;
SoftwareSerial ss(ARDUINO_GPS_TX , ARDUINO_GPS_RX);
#define gpsPort ss
#define rxPin 9
#define txPin 8
SoftwareSerial sim800(txPin,rxPin);
const char FIREBASE_HOST[] = "realtimedatabase.firebaseio.com";
const String FIREBASE_AUTH = "";
const String FIREBASE_PATH = "/gps-data/coordinate/employee_03";
const int SSL_PORT = 443;
char apn[] = "";
char user[] = "";
char pass[] = "";
TinyGsm modem(sim800);
TinyGsmClientSecure gsm_client_secure_modem(modem,0);
HttpClient http_client = HttpClient(gsm_client_secure_modem, FIREBASE_HOST, SSL_PORT);
unsigned long previousMillis = 0;
void setup()
{
Serial.begin(9600);
gpsPort.begin(9600);
Serial.println(F("gps serial initialize"));
sim800.begin(9600);
Serial.println(F("SIM800A serial initialize"));
Serial.println(F("Initializing modem..."));
modem.init();
String modemInfo = modem.getModemInfo();
Serial.print(F("Modem: "));
Serial.println(modemInfo);
http_client.setHttpResponseTimeout(10 * 1000);
}
void loop()
{
Serial.print(F("Connecting to "));
Serial.print(apn);
if (!modem.gprsConnect(apn, user, pass))
{
Serial.println(F(" fail"));
//delay(1000);
return;
}
Serial.println(F(" OK"));
if (modem.isGprsConnected()) { Serial.println("GPRS connected"); }
http_client.connect(FIREBASE_HOST, SSL_PORT);
while (true) {
if (!http_client.connected())
{
Serial.println();
http_client.stop();// Shutdown
Serial.println(F("HTTP not connected"));
break;
}
else
{
//ss.listen();
gps_loop();
}
}
}
void PostToFirebase(const char* method, const String & path , const String & data, HttpClient* http)
{
String response;
int statusCode = 0;
http->connectionKeepAlive();
String url;
if (path[0] != '/')
{
url = "/";
}
url += path + ".json";
url += "?auth=" + FIREBASE_AUTH;
Serial.print("POST:");
Serial.println(url);
Serial.print("Data:");
Serial.println(data);
String contentType = "application/json";
http->put(url, contentType, data);
statusCode = http->responseStatusCode();
Serial.print(F("Status code: "));
Serial.println(statusCode);
response = http->responseBody();
Serial.print(F("Response: "));
Serial.println(response);
if (!http->connected())
{
Serial.println();
http->stop();// Shutdown
Serial.println(F("HTTP POST disconnected"));
}
}
void gps_loop()
{
// ss.listen();
boolean newData = false;
for (unsigned long start = millis(); millis() - start < 2000;){
//ss.listen();
while (ss.available()){
if (tinyGPS.encode(ss.read())){
newData = true;
break;
}
}
}
if(true){
newData = false;
String latitude, longitude;
latitude = String(tinyGPS.location.lat(), 6);
longitude = String(tinyGPS.location.lng(), 6);
Serial.print("Latitude= ");
Serial.print(latitude);
Serial.print(" Longitude= ");
Serial.println(longitude);
String gpsData = "{";
gpsData += "\"lat\":" + latitude + ",";
gpsData += "\"lng\":" + longitude + "";
gpsData += "}";
PostToFirebase("PATCH", FIREBASE_PATH, gpsData, &http_client);
}
}
Error
gps serial initialize
SIM800A serial initialize
Initializing modem...
Modem: SIM800 R14.18
Connecting to apn OK
GPRS connected
HTTP not connected
Connecting to apn OK
GPRS connected
I have tried using ESP8266 (Wemos D1 R1) to save my GPS data to the database via WiFi, and that worked. Now, the problem is I can't connect to the firebase database using my Arduino and SIM800L. What should I do?