Wio Terminal httpCode <= 0

[Citric]

For the sample code we provide:

/**
   BasicHTTPSClient.ino
    Created on: 14.10.2018
*/

#include <Arduino.h>
#include <rpcWiFi.h>
#include <HTTPClient.h>
#include <WiFiClientSecure.h>

const char* test_root_ca = \
                            "-----BEGIN CERTIFICATE-----\n"
                            "MIIDrzCCApegAwIBAgIQCDvgVpBCRrGhdWrJWZHHSjANBgkqhkiG9w0BAQUFADBh\n"
                            "MQswCQYDVQQGEwJVUzEVMBMGA1UEChMMRGlnaUNlcnQgSW5jMRkwFwYDVQQLExB3\n"
                            "d3cuZGlnaWNlcnQuY29tMSAwHgYDVQQDExdEaWdpQ2VydCBHbG9iYWwgUm9vdCBD\n"
                            "QTAeFw0wNjExMTAwMDAwMDBaFw0zMTExMTAwMDAwMDBaMGExCzAJBgNVBAYTAlVT\n"
                            "MRUwEwYDVQQKEwxEaWdpQ2VydCBJbmMxGTAXBgNVBAsTEHd3dy5kaWdpY2VydC5j\n"
                            "b20xIDAeBgNVBAMTF0RpZ2lDZXJ0IEdsb2JhbCBSb290IENBMIIBIjANBgkqhkiG\n"
                            "9w0BAQEFAAOCAQ8AMIIBCgKCAQEA4jvhEXLeqKTTo1eqUKKPC3eQyaKl7hLOllsB\n"
                            "CSDMAZOnTjC3U/dDxGkAV53ijSLdhwZAAIEJzs4bg7/fzTtxRuLWZscFs3YnFo97\n"
                            "nh6Vfe63SKMI2tavegw5BmV/Sl0fvBf4q77uKNd0f3p4mVmFaG5cIzJLv07A6Fpt\n"
                            "43C/dxC//AH2hdmoRBBYMql1GNXRor5H4idq9Joz+EkIYIvUX7Q6hL+hqkpMfT7P\n"
                            "T19sdl6gSzeRntwi5m3OFBqOasv+zbMUZBfHWymeMr/y7vrTC0LUq7dBMtoM1O/4\n"
                            "gdW7jVg/tRvoSSiicNoxBN33shbyTApOB6jtSj1etX+jkMOvJwIDAQABo2MwYTAO\n"
                            "BgNVHQ8BAf8EBAMCAYYwDwYDVR0TAQH/BAUwAwEB/zAdBgNVHQ4EFgQUA95QNVbR\n"
                            "TLtm8KPiGxvDl7I90VUwHwYDVR0jBBgwFoAUA95QNVbRTLtm8KPiGxvDl7I90VUw\n"
                            "DQYJKoZIhvcNAQEFBQADggEBAMucN6pIExIK+t1EnE9SsPTfrgT1eXkIoyQY/Esr\n"
                            "hMAtudXH/vTBH1jLuG2cenTnmCmrEbXjcKChzUyImZOMkXDiqw8cvpOp/2PV5Adg\n"
                            "06O/nVsJ8dWO41P0jmP6P6fbtGbfYmbW0W5BjfIttep3Sp+dWOIrWcBAI+0tKIJF\n"
                            "PnlUkiaY4IBIqDfv8NZ5YBberOgOzW6sRBc4L0na4UU+Krk2U886UAb3LujEV0ls\n"
                            "YSEY1QSteDwsOoBrp+uvFRTp2InBuThs4pFsiv9kuXclVzDAGySj4dzp30d8tbQk\n"
                            "CAUw7C29C79Fv1C5qfPrmAESrciIxpg0X40KPMbp1ZWVbd4=\n"
                            "-----END CERTIFICATE-----\n";

WiFiClientSecure client;

void setup() {

  Serial.begin(115200);

  Serial.println();
  Serial.println();
  Serial.println();

  WiFi.mode(WIFI_STA);
  WiFi.begin("CHCK", "depot0510");

  // wait for WiFi connection
  Serial.print("Waiting for WiFi to connect...");
  while ((WiFi.status() != WL_CONNECTED)) {
    Serial.print(".");
  }
  Serial.println(" connected");
  client.setCACert(test_root_ca);
}

void loop() {
  if(&client) {
    {
      // Add a scoping block for HTTPClient https to make sure it is destroyed before WiFiClientSecure *client is 
      HTTPClient https;
  
      Serial.print("[HTTPS] begin...\n");
      if (https.begin(client, "https://www.example.com/index.html")) {  // HTTPS
        Serial.print("[HTTPS] GET...\n");
        // start connection and send HTTP header
        int httpCode = https.GET();
  
        // httpCode will be negative on error
        if (httpCode > 0) {
          // HTTP header has been send and Server response header has been handled
          Serial.printf("[HTTPS] GET... code: %d\n", httpCode);
  
          // file found at server
          if (httpCode == HTTP_CODE_OK || httpCode == HTTP_CODE_MOVED_PERMANENTLY) {
            String payload = https.getString();
            Serial.println(payload);
          }
        } else {
          Serial.printf("[HTTPS] GET... failed, error: %s\n", https.errorToString(httpCode).c_str());
        }
  
        https.end();
      } else {
        Serial.printf("[HTTPS] Unable to connect\n");
      }
      // End extra scoping block
    }
  
  } else {
    Serial.println("Unable to create client");
  }

  Serial.println();
  Serial.println("Waiting 10s before the next round...");
  delay(10000);
}

After testing, we found that "https.begin(client, "https://www.example.com/index.html")" is only suitable for “Example Domain” This site. If you change the website, you will not be able to connect. Since we are currently in China and cannot connect to the Google network, there is no way to test the connection of Google for you, but we have tested several websites. Removing the client parameter can solve the connection problem well, namely:
https.begin(“URL”)