Code isn't working without connected Blynk

If it is declared as global it should be unsigned long timeout; as there is no point in initializing there a global variable with mills(), you assign mills()/1000 later in setup just before while loop. However if the variable is used as local in setup then you initialize and declare variable inline just before while loop like so: unsigned long timeout = mills() / 1000; (same as your last line), you probably misunderstood me as for the first part.

Anyway the whole thing with while loop is not needed as you can simply use Blynk.connect(3333); which will do the same.

@conkerkh do you actually use Blynk.connect(timeout); in your sketches?

With Blynk.connect(1); i.e 3 milliseconds I get:

[4868] Blynk v0.3.4
[5001] Connecting to
[5351] Ready (ping: 1ms).

This suggests it took 351 milliseconds to connect so why didn’t it skip through the timeout after 3ms?

Tried several connections and even with almost 5 seconds to connect it still doesn’t skip the timeout.

[5865] Blynk v0.3.4
[5865] Connecting to
[11225] Connecting to
[11545] Ready (ping: 0ms).

thanks for clearing things up. i was asked to follow exact code examples, this is why i used ‘as is’.

unfortunately for the next days i will not have access to the arduino + ethernet modul. but later i will test your suggestion too, and announce if it works or not.

It’s a while condition not a timer interrupt so in this case you wont see timeout after 3ms but it will occur when run() finishes execution and at the same time while loop checked that it is executing for more than 3ms.

1 Like

Hi @wanek

I’m wondering if you ever resolved your connection issues as discussed in this thread? I am looking for a solution for the same problem. I would like to use Blynk.connect() instead of Blynk.begin() so I can run the code even when internet connection is down.

I am experiencing the same problems as you have described.


the short answer is yes. but not was as simple as i thought…
i also have to mention, that i’m not really good at oop, so probably, there are more elegant ways to solve this problem.

i still do not understand why everybody thinks, that a sketch should work only with network connection. yes, it is very nice to use the blynk app, but sometimes the arduino should work even without internet… so, here is what i did (only the relevant code):


 There is a bug in blynk library (v0.3.4), which hangs the Blynk.begin(auth) function (keeps restarting the board every minute), if there is no network access during startup. To bypass this problem, edit this file in:
  libraries\Blynk\Adapters\BlynkEthernet.h, at line 58:

  comment out the: BLYNK_FATAL("DHCP Failed!"); line,

  and insert these lines:
  BLYNK_LOG("DHCP failed. check your network connection!");
  BLYNK_LOG("bypassing blynk...");


// global variables
bool blynkAllowed = true;
bool firstConnect = true;

void setup()
  Blynk.begin(auth);       // configuring ethernet. timeout: 60 seconds

  if (millis() < 50000) {  // if Blynk.begin(auth) finished under 50 seconds == connected to network
    beep(500, 0);
    //Serial.println("connected to local network!");

    tryConnecting();                          // try to connect to blynk server
    tryConnecting();                          // i put this twice, because very rarely it fails the first connection

    timer.setInterval(1000, updateBlynk);     // set how often send data to the blynk server
    timer.setInterval(60000, tryConnecting);  // if lost connection, try to connect time by time

    //Serial.println("reconnect attempts to blynk server allowed in main loop");
  else {                   // if Blynk.begin(auth) took more than 50 seconds == no network connection
    blynkAllowed = false;
    beep(2000, 0);

    //Serial.println("no network access. no reconnect attempts will be allowed in main loop");

void loop()
  checkBlynk();;  // initiates SimpleTimer

void checkBlynk()
  if (blynkAllowed) {
    if (firstConnect) tryConnecting();
    if (Blynk.connected());

void tryConnecting()
  if (!Blynk.connected()) {
    Blynk.connect();  // try to connect for 15 seconds, every time, as set  in: timer.setInterval(60000, tryConnecting) in void setup
                      // but let the main loop run

    if (Blynk.connected()) {
      if (firstConnect) {
        // do some none relevant stuff here, and
        firstConnect = false;
      //Serial.println("connected to blynk server!");
      beep(500, 0);

i hope the code + comments are self explanatory. check it out, and let me know if this works for you. since when i wrote this code, there are newer library versions, but afaik this specific situation was not resolved.

*edit: of course, do not forget, to close the arduino ide before editing the lib file, and open the ide only after you saved the file.

1 Like

Hi @wanek,

Thankyou very much for sharing your solution. I will try and implement what you have done and let you know if it works for me. Well done for working it out.

Nick Murray

@wanek I have implemented the code you suggested and made the changes in the Blynk library file. It works well for me. Thanks again for the solution.

i’m glad that could help.

I am facing same problem.I am using Nodemcu ESP8266 12e.
This my original code

#define BLYNK_PRINT Serial // Comment this out to disable prints and save 
#include <ESP8266WiFi.h>
#include <BlynkSimpleEsp8266.h>
#include <SimpleTimer.h>
#include <TimeLib.h>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = "xxxxxxxxxxxxxxxxxxx";

// Set your LED and physical button pins here
const int ledPin = 16;
const int btnPin = 5;

SimpleTimer timer;
void checkPhysicalButton();

int ledState = LOW;
int btnState = HIGH;
void sendUptime() {
  Blynk.virtualWrite(V20, millis() / 60000);
  long rssi = WiFi.RSSI();
  Blynk.virtualWrite(V15, rssi);
void setup()
  pinMode(ledPin, OUTPUT);
  pinMode(btnPin, INPUT_PULLUP);
  digitalWrite(ledPin, ledState);
  timer.setInterval(100L, checkPhysicalButton);
  Blynk.begin(auth, "xxxxxxx", "xxxxxxx");
while (Blynk.connect() == false) {
    // Wait until connected

timer.setInterval(60000L, sendUptime);
  // Setup a function to be called every 100 ms

bool isFirstConnect = true;

// This function will run every time Blynk connection is established
  if (isFirstConnect) {  
    isFirstConnect = false;

// When App button is pushed - switch the state
  ledState = param.asInt();
  digitalWrite(ledPin, ledState);

void checkPhysicalButton()
  if (digitalRead(btnPin) == LOW) {
    // btnState is used to avoid sequential toggles
    if (btnState != LOW) {

      // Toggle LED state
      ledState = !ledState;
      digitalWrite(ledPin, ledState);

      // Update Button Widget
      Blynk.virtualWrite(V2, ledState);
    btnState = LOW;
  } else {
    btnState = HIGH;

void loop()
{;; // Run Blynk
  // Run SimpleTimer

I have tried your code but got many errors. can explain how to implement this your my code???
I am using Nodemcu ESP 8266 12e.

What errors did you get?

The above code works fine when it connected to internet .
But doesn’t works when wiffi router is off.
I have connected physical buttons they should works when internet is off / wiffi router is off.
Plz guys help me.

@saurabh47 study this post in detail Check connection status in loop and reconect


Did you ever get your arduino Sketch to run when Blynk is not connected to the internet?

No ,i don’t get.
I was is search of this but know i’m working on different project.

It’s a little more complicated than it first seems but the 2 basic steps are:

'1. Bail out of the while loop that you MUST have in setup()

int mytimeout = millis() / 1000;
while (Blynk.connect() == false) { 
  if((millis() / 1000) > mytimeout + 8){  // try for less than 9 seconds

'2. Only process in the main loop() when you are connected.


Further requirements are SimpleTimer to check if router / server is now running so a connection to Blynk can be made etc.



Hi, I’m new to blynk and not that good with codes…
I copy/paste your codes and added the libraries (i got them
from the blynk ethernet sample)
#define BLYNK_PRINT Serial
#include <SPI.h>
#include <Ethernet.h>
#include <BlynkSimpleEthernet.h>

I’m using W5100
I did the changes to the blynk library
Getting the error:
‘beep’ was not declared in this scope

Am I missing any libraries or something?
Any help would be great! (Emphasis on “im no good at coding”) :slight_smile:

beep() is a standard Arduino function so I don’t know why you have a problem with it.

Just comment the line out for now and proceed with out.


beep() is just a function i declared somewhere else, in my sketch, it is used to generate buzzer sounds, if an event occurs.

as costas said, you can safely delete them, no problem. otherwise, the code should work. i’m using this in a home automation project, the arduino have to run continuously, even when there is no internet connection, because the physical light switches are wired to the arduino.

Got it, i commented out all the beep, now I got a new error:
‘updateBlynk’ was not declared in this scope

really sorry for stupid questions. I’m just totally bad at this, but your code is the exact thing I need for my project. :grin:

I think I should not comment it out (looks important i guess), but when I did (just for the sake of uploading) the device was not able to connect (but it kept on trying though)
any thoughts? (I can connect fine when i use the default sample files (ethernet & usb)