ESP32 doesn't connect to my API REST (uses HTTPS). PLS HELP

[nandostreet]

I'm sending a JSON to my HTTPS REST API, but it's not working. (I'm also sending information to an MQTT broker and to my WhatsApp using a bot, but that part works well).
BOARD: ESP32 DEV MODULE

The code (I errased the sensitive parts like passwords, etc.):

#include <Arduino.h>
#include <WiFi.h>
#include <HTTPClient.h>
#include <PubSubClient.h>
// MONGODB
#include <ArduinoJson.h>
#include <WiFiClientSecure.h>

const char *ssid = "";
const char *password = "";
int contconexion;
String url;

// MONGODB
// The REST API endpoint 
const char *base_rest_url = "";
// Size of the JSON document. Use the ArduinoJSON JSONAssistant
const int JSON_DOC_SIZE = 384;

String apiKey_1 = "";
String numero_tlf_1 = "";

String str = "";

const char separator = ',';
const int dataLength = 1;
String data[dataLength];

const char *mqtt_broker = "broker.emqx.io";
const char *topic = "";
const char *topic0 = "";
const char *mqtt_username = "";
const char *mqtt_password = "";
const int mqtt_port = ;

WiFiServer server(80);

WiFiClient espClient;
PubSubClient client(espClient);

// MONGO
HTTPClient http;
WiFiClientSecure wifiClientAPI;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED and contconexion < 50) {
    ++contconexion;
    delay(500);
    Serial.print(".");
  }
  if (contconexion < 50) {
    Serial.println("");
    Serial.print("Successful Connection: ");
    Serial.println(WiFi.localIP());
    server.begin();
  }

  client.setServer(mqtt_broker, mqtt_port);
  client.setCallback(callback);
  while (!client.connected()) {
    String client_id = "esp32-client-";
    client_id += String(WiFi.macAddress());
    Serial.printf("Client %s connected to the MQTT broker\n", client_id.c_str());
    if (client.connect(client_id.c_str(), mqtt_username, mqtt_password)) {
      Serial.println("EMQX MQTT public broker connected");
    } else {
      Serial.print("failed with state ");
      Serial.print(client.state());
      delay(2000);
    }
  }

  String stringOne = "Connected";
  char Buf[50];
  stringOne.toCharArray(Buf, 50);
  client.publish(topic, Buf);
  client.subscribe(topic0);
}

void loop() {
  client.loop();

  if (Serial.available()) {
    str = Serial.readStringUntil('\n');
    for (int i = 0; i < dataLength; i++) {
      int index = str.indexOf(separator);
      data[i] = str.substring(0, index);
      str = str.substring(index + 1);
    }
    String stringOne = "Subject Registered: " + String(data[0]) + " attended";

    char Buf[170];
    stringOne.toCharArray(Buf, 170);
    client.publish(topic, Buf);
    sendPostRequest(String(data[0]));
    delay(2000);
    message_to_whatsapp(stringOne);
  }
}

void message_to_whatsapp(String message) {
  url = "https://api.callmebot.com/whatsapp.php?phone=" + numero_tlf_1 + "&text=" + urlencode(message) + "&apikey=" + apiKey_1;
  postData();
}

void postData() {
  int httpCode;     // variable used to get the response http code after calling the API
  HTTPClient http;  // Declare an object of class HTTPClient
  http.begin(url);  // begin the HTTPClient object with the generated URL
  httpCode = http.POST(url);
  if (httpCode == 200)      // Check if the response http code is 200
  {
    Serial.println("Sent to EMQX successfully"); // print message sent ok message
  } else                      // if response HTTP code is not 200 it means there is some error.
  {
    Serial.println("Not sent to EMQX"); // print error message.
  }
  http.end();          // After calling the API end the HTTP client object.
}

void callback(char *topic0, byte *payload, unsigned int length) {
  Serial.print("Message arrived in topic: ");
  Serial.println(topic0);
  Serial.print("Message:");
  for (int i = 0; i < length; i++) {
    Serial.print((char) payload[i]);
  }
  Serial.println();
  Serial.println("-----------------------");
}

String urlencode(String str)  // Function used for encoding the URL
{
  String encodedString = "";
  char c;
  char code0;
  char code1;
  char code2;
  for (int i = 0; i < str.length(); i++) {
    c = str.charAt(i);
    if (c == ' ') {
      encodedString += '+';
    } else if (isalnum(c)) {
      encodedString += c;
    } else {
      code1 = (c & 0xf) + '0';
      if ((c & 0xf) > 9) {
        code1 = (c & 0xf) - 10 + 'A';
      }
      c = (c >> 4) & 0xf;
      code0 = c + '0';
      if (c > 9) {
        code0 = c - 10 + 'A';
      }
      code2 = '\0';
      encodedString += '%';
      encodedString += code0;
      encodedString += code1;
    }
    yield();
  }
  return encodedString;
}

// MONGODB
void sendPostRequest(String name) {

  char rest_api_url[200];
  // Calling our API server
  sprintf(rest_api_url, "%sfingerprint/post", base_rest_url);
  Serial.println(rest_api_url);

  // Create a JSON object with the "name" field
  StaticJsonDocument<JSON_DOC_SIZE> jsonDocument;
  jsonDocument["name"] = name;

  // Serialize the JSON into a string
  String jsonData;
  serializeJson(jsonDocument, jsonData);
  Serial.println("JSON Data...");
  Serial.println(jsonData);

  // Initialize the HTTP request
  http.begin(wifiClientAPI, rest_api_url);

  // Set a header to indicate that you are sending JSON
  http.addHeader("Content-Type", "application/json");

  // Perform the HTTP POST request
  int httpResponseCode = http.POST(jsonData);

  if (httpResponseCode > 0) {
    Serial.print("Successful HTTP POST. Response code: ");
    Serial.println(httpResponseCode);

    // You can print the server's response if needed
    String response = http.getString();
    Serial.println(response);
  } else {
    Serial.print

("Error in POST request. Response code: ");
    Serial.println(httpResponseCode);
  }

  // End the HTTP request
  http.end();
}

The error I get is this:

Error in POST request. Response code: -1

[nandostreet]

Pls someone help me