added debug information

esp8285/lib/AliyunIoTSDK/src/AliyunIoTSDK.cpp

@@ -132,7 +132,7 @@ int AliyunIoTSDK::mqttCheckConnect() {
             connectRetry = 0;
             while (false == client->connected()) {
                 client->disconnect();
-                Serial.print("INFO: Connecting to MQTT Server, clientId = ");
+                Serial.print("INFO: Connecting to Aliyun MQTT Server, clientId = ");
                 Serial.print(clientId);
                 Serial.print(", mqttUserName = ");
                 Serial.print(mqttUsername);
@@ -145,6 +145,7 @@ int AliyunIoTSDK::mqttCheckConnect() {
                 } else {
                     Serial.print("ERROR: MQTT Connect err: ");
                     Serial.println(client->state());
+                    client->disconnect();
                     delay(MQTT_WAIT_GENERIC);
                     connectRetry++;
                     Serial.print("INFO: Aliot connection retry: ");

esp8285/src/aliot_client.cpp

@@ -62,7 +62,7 @@ int connectToAliot(PubSubClient& mqtt_client) {
     if (0 == res && mqtt_client.connected()) {
         INFOF("Aliyun IoT connected\n");
     } else {
-        ERRORF("Failed to connect to Aliyun IoT\n");
+        ERRORF("Failed to connect to Aliyun IoT : %d\n", res);
         res = -1;
     }
     return res;

esp8285/src/iot_hub.cpp

@@ -139,6 +139,8 @@ void keepAliveIot() {
     unsigned long current_time = millis();
     if (current_time - last_check_time > 10000) {
         if (!g_mqtt_client.connected()) {
+            ERRORF("MQTT client is not connected, force disconnect and retry\n");
+            g_mqtt_client.disconnect();
             g_mqtt_client.unsubscribe(g_downstream_topic.c_str());
             g_subscribed = false;
             connectIot();