ESP8266 stuck at "Connecting to server..." when using Stream and Async Set simultaneously

[kaizennkhususco-pilot]

Describe the issue
I am experiencing a persistent "Connecting to server..." debug message when trying to send data (Set) while a Stream is active. Even though the Free Heap is sufficient (~20KB) and SSL buffer sizes have been limited, The AsyncClient seems to have failed to complete the handshake process for the "Set" task.

Hardware and Environment:
Board: ESP8266 (NodeMCU)
Library Version: FirebaseClient (latest)

here is the code that I wrote :

#define ENABLE_USER_AUTH
#define ENABLE_DATABASE

#include <ESP8266WiFi.h>
#include <FirebaseClient.h>
#include <FirebaseJson.h>
#include <Servo.h>
#include <DHT.h>
#include <WiFiClientSecure.h>
#include <config.h>

#define WIFI_SSID WIFI_SSID
#define WIFI_PASSWORD WIFI_PASSWORD

#define API_KEY API_KEY
#define USER_EMAIL USER_EMAIL
#define USER_PASSWORD USER_PASSWORD
#define DATABASE_URL DATABASE_URL

#define LED_PIN D6
#define SERVO_PIN D4
#define DHT_PIN D2
#define DHTTYPE DHT11

unsigned long lastSensor = 0;
const unsigned long interval = 5000;

Servo myServo;
DHT dht(DHT_PIN, DHTTYPE);

void processData(AsyncResult &aResult);

WiFiClientSecure ssl_client, ssl_stream_client;

using AsyncClient = AsyncClientClass;
AsyncClient aClient(ssl_client), streamClient(ssl_stream_client);

UserAuth user_auth(API_KEY, USER_EMAIL, USER_PASSWORD);
FirebaseApp app;
RealtimeDatabase Database;

bool onetimeTest = false;

void setup() {
  Serial.begin(115200);

  pinMode(LED_PIN, OUTPUT);
  myServo.attach(SERVO_PIN);
  dht.begin();

  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);

  while (WiFi.status() != WL_CONNECTED) {
    Serial.print(".");
    delay(300);
  }
  Serial.println();
  Serial.print("[CONNECTED!] ip address : ");
  Serial.println(WiFi.localIP());
  Serial.println();

  ssl_client.setInsecure();
  ssl_stream_client.setInsecure();

  ssl_client.setBufferSizes(1024, 1024); 
  ssl_stream_client.setBufferSizes(1024, 1024);

  initializeApp(aClient, app, getAuth(user_auth), processData, "🔐 authTask");
  app.getApp<RealtimeDatabase>(Database);
  Database.url(DATABASE_URL);

  Database.get(streamClient, "/iot_system/control", processData, true, "streamTask");
}

void loop() {
  app.loop();

  if (app.ready() && !onetimeTest) {
    onetimeTest = true;
  }

  if (app.ready()) {
    if (millis() - lastSensor >= 5000) { 
      lastSensor = millis();

      float t = dht.readTemperature();
      float h = dht.readHumidity();

      if (!isnan(t) && !isnan(h)) {
        checkMemory("BEFORE SEND");
        Serial.printf("Update Data... Suhu: %.1f, Hum: %.1f\n", t, h);
        
        Database.set<float>(aClient, "/iot_system/sensor/temp", t, processData, "setSuhuTask");
        Database.set<float>(aClient, "/iot_system/sensor/hum", H, processData, "setHumTask");
      } else {
        Serial.println("Gagal baca sensor!");
        checkMemory("AFTER SEND");
      }
    }
  }
}

void processData(AsyncResult &aResult) {
  if (!aResult.isResult())
    return;

  if (aResult.isEvent())
    Firebase.printf("Event task: %s, msg: %s, code: %d\n", aResult.uid().c_str(), aResult.eventLog().message().c_str(), aResult.eventLog().code());

  if (aResult.isDebug())
    Firebase.printf("Debug task: %s, msg: %s\n", aResult.uid().c_str(), aResult.debug().c_str());

  if (aResult.isError())
    Firebase.printf("Error task: %s, msg: %s, code: %d\n", aResult.uid().c_str(), aResult.error().message().c_str(), aResult.error().code());

  if (aResult.available() && aResult.uid() == "streamTask") {
    Firebase.printf("task: %s, payload: %s\n", aResult.uid().c_str(), aResult.c_str());

    RealtimeDatabaseResult &stream = aResult.to<RealtimeDatabaseResult>();

    Serial.println("Path: " + aResult.path());

    String jsonStr = stream.to<String>();

    Serial.println("JSON: " + jsonStr);

    FirebaseJson json;
    FirebaseJsonData data;

    json.setJsonData(jsonStr);

    if (json.get(data, "led")) {
        int ledValue = data.to<int>();

        Serial.print("LED: ");
        Serial.println(ledValue);

        digitalWrite(LED_PIN, ledValue ? HIGH : LOW);
    }

    if (json.get(data, "servo")) {
        int servoValue = data.to<int>();

        Serial.print("Servo: ");
        Serial.println(servoValue);

        myServo.write(servoValue);
    }
  }
}

void checkMemory(String label) {
  Serial.print("[" + label + "] ");
  Serial.print("Free Heap: ");
  Serial.print(ESP.getFreeHeap());
  Serial.print(" | Max Block: ");
  Serial.println(ESP.getMaxFreeBlockSize());
}

and this is the output that makes me confused as to why this could happen:

[BEFORE SEND] Free Heap: 21456 | Max Block: 15432
Debug task: setSuhuTask, msg: Connecting to server...
Debug task: setHumTask, msg: Connecting to server...
(No further response or error code)

[mobizt]

It depends on your database structure, data to handle may be larger than the ssl buffer to handle for valid ssl data decryption as the data is truncated and gives no data from SSL client then it gets stuck.

Please try to increase the SSL client rx buffer size.

[kaizennkhususco-pilot]

OK, thank you in advance, mobizt.