Device was disconnected error

Hey,
i am trying to run a code with blynk but from time to time i get the Device was disconnected error.
this is the blynk serial:

[40093] Connecting to blynk-cloud.com:8442
[40715] Ready (ping: 1ms).
[51715] Connecting to blynk-cloud.com:8442
[52320] Ready (ping: 22ms).
[62850] Connecting to blynk-cloud.com:8442
[63529] Ready (ping: 23ms).
[73653] Connecting to blynk-cloud.com:8442
[74281] Ready (ping: 22ms).

i am also attaching my source code:

        #include <dht11.h>
        dht11 DHT11;
        #define DHT11PIN D2
        #define BLYNK_PRINT Serial
        #include <ESP8266WiFi.h>
        #include <BlynkSimpleEsp8266.h>
        char auth[] = "****";
        char ssid[] = "****";
        char pass[] = "****";
        BlynkTimer timer;
        WidgetLCD lcd(V0);
        int chk;
        String msg;
        void setup() {
          Serial.begin(115200);
          Blynk.begin(auth, ssid, pass);
          pinMode(D2, OUTPUT);
          pinMode(A0, INPUT);
          timer.setInterval(1000L, sendSensor);
          lcd.clear();
        }

    void loop() {
      Blynk.run();
      timer.run();
    }
    void sendSensor()
    {
      chk = DHT11.read(DHT11PIN);
      int sensorValue = analogRead(A0);
      int sensorPercentage = map(sensorValue, 280, 950, 100, 0);
       if(sensorValue >=1000){
              Blynk.virtualWrite(V7, 0);
              Blynk.virtualWrite(V8, 0);
              Blynk.virtualWrite(V9, 0);
        }
        if(sensorValue < 1000 && sensorValue >=600){
              Blynk.virtualWrite(V7, 1023);
              Blynk.virtualWrite(V8, 0);
              Blynk.virtualWrite(V9, 0);
        }
        if(sensorValue < 600 && sensorValue >= 370){
              Blynk.virtualWrite(V7, 0);
              Blynk.virtualWrite(V8, 1023);
              Blynk.virtualWrite(V9, 0);
        }
        if(sensorValue <370){
              Blynk.virtualWrite(V7, 0);
              Blynk.virtualWrite(V8, 0);
              Blynk.virtualWrite(V9, 1023);
        }
      Blynk.virtualWrite(V4, sensorValue);
      Blynk.virtualWrite(V2, DHT11.humidity);
      Blynk.virtualWrite(V3, DHT11.temperature);
      Blynk.virtualWrite(V6, sensorPercentage);
    }

hope someone can help me to make it stable

Your code looks pretty much ok to me. It could be the DHT library because I know for a fact that those sensors take some time to read.

What happens if you comment out the DHT parts?

@Yuval_Hirschmann including the if statement you have 7 consecutive virtualWrite() commands.

ESP’s with the ancient 2.3.0 core can handle 3 or 4.

So you need to split them up, even with a crude delay(50) or upgrade your version of ESP Arduino core.

2.40-rc1 has a memory leak bug in axTLS but it’s a simple patch https://github.com/igrr/axtls-8266/pull/50/files

Alternatively use the master branch which will have a few more fixes included.