Vodacom South Africa 3G data connection, is blocking/dropping Blynk-cloud

patrickiot · March 26, 2019, 2:39pm

After the device (NodeMCU) connects to wifi, obtains a local IP address (from the Smartphone tethered wifi DHCP), connects to the mobile ISP DNS and obtains the blynk-cloud IP address, attempts to connect to blynk-cloud and sends my Auth Token, the blynk client reports time-out, and never gets the “>[00|00|01|00|C8]” messages from Blynk-cloud.

Background:
I purchased a low-cost cellphone (MobiWire Sakari) which I want to use as my IOT device’s internet connection to Blynk-Cloud (instead of say, SIM900 etc). The cellphone has wifi-tethering and I requested an unrestricted APN on the SIM from the Cellular provider. I loaded data time, and was able to browse from the smartphone OK. Next I tested the tethering by connecting to the smartphone from my PC WIFI dongle, all good with internet browsing etc. Next I tried accessing my Blynk-cloud project from the PC tethered to the smartphone, it works OK with MS explorer and telnet and returns the correct HTML/Json script information for my project on blynk-cloud.

However, when I tried the Blynk ESP8266 example sketch on an NodeMCU via the tethered smartphone, the connection stalls and times out after the DNS look-up of Blynk-Cloud.com and the initial IP connection attempt and just after my Blynk example sketch debug shows sending the Auth Token. The next thing that happens is that the device attempts to connect again by doing the DNS lookup again, so it seems like my device is not getting authenticated by the Blynk-cloud server at 45.55.96.146 or the latency is too high
If I try connecting via my home Broadband WIFI router it works perfectly.
I loaded an ESP8266/Arduino HTTP client example sketch from my Arduino IDE to the NodeMCU and it works perfectly to blynk-cloud via the tethered smartphone.

I tried increasing the network timeout time (>6000mS!) in the Blynkconfig.h with no luck.
I tried using LWIP 1.4, no luck.
I tried ports 80 and 8080, no luck.

All my other IOT projects (MQTT etc) seem to be connecting OK through the tethered smartphone.

I tried a different smartphone using the same SIM, same result.

At first I thought it may be an issue with my mobile data provider blocking ports, however it is working when I use a PC internet browser and I have tested using both 80 and 8080 ports using http://portquiz.net/
I am unable to wireshark the link so I have just made serial output dumps for debugging.

Platform:
NodeMCU 0,9. (ESP-12e)
Arduino core: SDK:3.0.0-dev(c0f7b44)/Core:2.5.0=20500000/lwIP:STABLE-2_1_2_RELEASE/glue:1.1/BearSSL:6778687

Blynk Library 0.5.4
ESP8266: ESP ardjuino communitity core - 2.5.0 (non Git version)
IDE: Arduino/Windows 64 1.8.5
LWIP: V2 Lower Memory.

Blynk Sketch:

  Download latest Blynk library here:
    https://github.com/blynkkk/blynk-library/releases/latest

  Blynk is a platform with iOS and Android apps to control
  Arduino, Raspberry Pi and the likes over the Internet.
  You can easily build graphic interfaces for all your
  projects by simply dragging and dropping widgets.

    Downloads, docs, tutorials: http://www.blynk.cc
    Sketch generator:           http://examples.blynk.cc
    Blynk community:            http://community.blynk.cc
    Follow us:                  http://www.fb.com/blynkapp
                                http://twitter.com/blynk_app

  Blynk library is licensed under MIT license
  This example code is in public domain.

 *************************************************************

  You’ll need:
   - Blynk App (download from AppStore or Google Play)
   - ESP8266 board
   - Decide how to connect to Blynk
     (USB, Ethernet, Wi-Fi, Bluetooth, ...)

  There is a bunch of great example sketches included to show you how to get
  started. Think of them as LEGO bricks  and combine them as you wish.
  For example, take the Ethernet Shield sketch and combine it with the
  Servo example, or choose a USB sketch and add a code from SendData
  example.
 *************************************************************/

/* Comment this out to disable prints and save space */

#define BLYNK_PRINT Serial // Defines the object that is used for printing  these have to be here not lower in the code
#define BLYNK_DEBUG        // Optional, this enables more detailed prints

#include <ESP8266WiFi.h>
#include <BlynkSimpleEsp8266.h>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = "c2700ca3f8fa4bb9b03d8d6c778a8f40";

// Your WiFi credentials.
// Set password to "" for open networks.
char ssid[] = "Grace 3G";
char pass[] = "11111111";

//char ssid[] = "Love";
//char pass[] = "A850F3619D";

void setup()
{
  // Debug console
  Serial.begin(9600);

  //Blynk.begin(auth, ssid, pass);
  // You can also specify server:
  Blynk.begin(auth, ssid, pass, "blynk-cloud.com", 8080);
  //Blynk.begin(auth, ssid, pass, IPAddress(192,168,1,100), 8080);
}

void loop()
{
  Blynk.run();
  // You can inject your own code or combine it with other sketches.
  // Check other examples on how to communicate with Blynk. Remember
  // to avoid delay() function!
}

Library used:

/**
 * @file       BlynkConfig.h
 * @author     Volodymyr Shymanskyy
 * @license    This project is released under the MIT License (MIT)
 * @copyright  Copyright (c) 2015 Volodymyr Shymanskyy
 * @date       Jan 2015
 * @brief      Configuration of different aspects of library
 *
 */

#ifndef BlynkConfig_h
#define BlynkConfig_h

#include <Blynk/BlynkDetectDevice.h>

/***************************************************
 * Change these settings to match your need
 ***************************************************/

#define BLYNK_DEFAULT_DOMAIN     "blynk-cloud.com"
#define BLYNK_DEFAULT_PORT       80
#define BLYNK_DEFAULT_PORT_SSL   8441

/***************************************************
 * Professional settings
 ***************************************************/
// Library version.
#define BLYNK_VERSION        "0.5.4"

// Heartbeat period in seconds.
#ifndef BLYNK_HEARTBEAT
#define BLYNK_HEARTBEAT      30
#endif

// Network timeout in milliseconds.
#ifndef BLYNK_TIMEOUT_MS
#define BLYNK_TIMEOUT_MS     6000UL
#endif

// Limit the amount of outgoing commands per second.
#ifndef BLYNK_MSG_LIMIT
#define BLYNK_MSG_LIMIT      15
#endif

// Limit the incoming command length.
#ifndef BLYNK_MAX_READBYTES
#define BLYNK_MAX_READBYTES  256
#endif

// Limit the outgoing command length.
#ifndef BLYNK_MAX_SENDBYTES
#define BLYNK_MAX_SENDBYTES  128
#endif

// Uncomment to use Let's Encrypt Root CA
//#define BLYNK_SSL_USE_LETSENCRYPT

// Uncomment to disable built-in analog and digital operations.
//#define BLYNK_NO_BUILTIN

// Uncomment to disable providing info about device to the server.
//#define BLYNK_NO_INFO

// Uncomment to enable debug prints.
//#define BLYNK_DEBUG

// Uncomment to force-enable 128 virtual pins
//#define BLYNK_USE_128_VPINS

// Uncomment to disable fancy logo
//#define BLYNK_NO_FANCY_LOGO

// Uncomment to enable 3D fancy logo
//#define BLYNK_FANCY_LOGO_3D

// Uncomment to enable experimental functions.
//#define BLYNK_EXPERIMENTAL

// Uncomment to disable all float/double usage
//#define BLYNK_NO_FLOAT

// Uncomment to switch to direct-connect mode
//#define BLYNK_USE_DIRECT_CONNECT


// Uncomment to append command body to header (uses more RAM)
//#define BLYNK_SEND_ATOMIC

// Split whole command into chunks (in bytes)
//#define BLYNK_SEND_CHUNK 64

// Wait after sending each chunk (in milliseconds)
//#define BLYNK_SEND_THROTTLE 10

#endif

IDE serial debugging of case where failure occurs:

 SDK:2.2.1(cfd48f3)/Core:2.4.2/lwIP:2.0.3(STABLE-2_0_3_RELEASE/glue:arduino-2.4.1-13-g163bb82)/BearSSL:6d1cefc
[55] Connecting to Grace 3G
scandone
scandone
state: 0 -> 2 (b0)
state: 2 -> 3 (0)
state: 3 -> 5 (10)
add 0
aid 1

connected with Grace 3G, channel 6
dhcp client start...
cnt 
wifi evt: 0
ip:192.168.43.213,mask:255.255.255.0,gw:192.168.43.1
wifi evt: 3
[2560] Connected to WiFi
[2560] IP: 192.168.43.213
[2561] 
    ___  __          __
   / _ )/ /_ _____  / /__
  / _  / / // / _ \/  '_/
 /____/_/\_, /_//_/_/\_\
        /___/ v0.5.4 on NodeMCU

[2570] Connecting to blynk-cloud.com:8080
[hostByName] request IP for: blynk-cloud.com
[hostByName] Host: blynk-cloud.com IP: 45.55.96.146
[3308] <[02|00|01|00] c2700ca3f8fa4bb9b03d8d6c778a8f40
[9310] Login timeout

IDE serial debugging of case where connection success occurs:

SDK:2.2.1(cfd48f3)/Core:2.4.2/lwIP:2.0.3(STABLE-2_0_3_RELEASE/glue:arduino-2.4.1-13-g163bb82)/BearSSL:6d1cefc
[55] Connecting to Love
wifi evt: 2
sta config unchangedscandone
scandone
state: 0 -> 2 (b0)
state: 2 -> 3 (0)
state: 3 -> 5 (10)
add 0
aid 5
cnt 

connected with Love, channel 3
dhcp client start...
wifi evt: 0
ip:192.168.88.251,mask:255.255.255.0,gw:192.168.88.1
wifi evt: 3
[329] Connected to WiFi
[355] IP: 192.168.88.251
[382] 
    ___  __          __
   / _ )/ /_ _____  / /__
  / _  / / // / _ \/  '_/
 /____/_/\_, /_//_/_/\_\
        /___/ v0.5.4 on NodeMCU

[536] Connecting to blynk-cloud.com:8080
[hostByName] request IP for: blynk-cloud.com
[hostByName] Host: blynk-cloud.com IP: 45.55.96.146
:ref 1
[1118] <[02|00|01|00] c2700ca3f8fa4bb9b03d8d6c778a8f40
:wr 37 37 0
:wrc 37 37 0
:ack 37
:rn 5
:c0 1, 5
[1340] >[00|00|01|00|C8]
[1340] Ready (ping: 221ms).
[1340] Free RAM: 47040
[1407] <[11|00|02|00]Hver[00]0.5.4[00]h-beat[00]30[00]buff-in[00]1024[00]dev[00]NodeMCU[00]build[00]Mar 26 2019 15:06:36[00]
:wr 77 77 0
:wrc 77 77 0
:ack 77
:rn 5
:c0 1, 5
[1741] >[00|00|02|00|C8]

When I connect via PC internet browser via tethered smartphone by sending:
http://blynk-cloud.com/c2700ca3f8fa4bb9b03d8d6c778a8f40/project

{"id":478616176,"parentId":-1,"isPreview":false,"name":"Washing Machine Aces","createdAt":1550243820511,"updatedAt":1553617722320,"widgets":[{"type":"LED","id":57718,"x":3,"y":3,"color":600084223,"width":1,"height":1,"tabId":0,"label":"washing machine power","isDefaultColor":true,"deviceId":0,"pinType":"VIRTUAL","pin":0,"pwmMode":false,"rangeMappingOn":false,"min":0.0,"max":0.0,"value":"0"},{"type":"TERMINAL","id":61856,"x":0,"y":0,"color":255,"width":8,"height":3,"tabId":0,"label":"Type 88  Then Send To Start","isDefaultColor":true,"deviceId":0,"pinType":"VIRTUAL","pin":1,"pwmMode":false,"rangeMappingOn":false,"min":0.0,"max":0.0,"autoScrollOn":true,"terminalInputOn":true,"textLightOn":true,"attachNewLine":false},{"type":"NOTIFICATION","id":99445,"x":0,"y":3,"color":600084223,"width":2,"height":1,"tabId":0,"isDefaultColor":true,"androidTokens":{"3aa1bab8731f139a":"e7Aqm0MxDYI:APA91bEwtGaKv8PXHF8A5K5c_RXvuRUHQfUiTtODOxn8HPYSG1X8JiDd3GedbKd2tDurl63bC5HXLdsbHlk-q3Jxa2IywCyojB-MhVF3QeQwfyGAr5zFi3UVqMsKq-DZg0P0NcdI7voS","d59ea18322402a4f":"dBF3CiPZGKA:APA91bHiIeR5ztQhKQCv7Qlae6jkntYoSRnXrp3uJ3S676WUHyOaDoj_rqQBUkrJMXuGXTa695FwBLYOdENaPIYQmgsrSjhnANcI9ZvYd-lYer_v8pfw4FT9FxNcABUyf9GPc-XTf9GN"},"notifyWhenOffline":true,"notifyWhenOfflineIgnorePeriod":0,"priority":"normal","soundUri":"content://settings/system/notification_sound"}],"devices":[{"id":0,"name":"washing machine ","boardType":"ESP8266","vendor":"washing machine ","connectionType":"WI_FI","isUserIcon":false}],"theme":"Blynk","keepScreenOn":false,"isAppConnectedOn":false,"isNotificationsOff":false,"isShared":false,"isActive":true,"widgetBackgroundOn":false,"color":0,"isDefaultColor":true}

Here is the Arduino ESP8266 HTTP client example sketch that does work OK via the tethered smartphone:

/**
   BasicHTTPClient.ino

    Created on: 24.05.2015

*/

#include <Arduino.h>

#include <ESP8266WiFi.h>
#include <ESP8266WiFiMulti.h>

#include <ESP8266HTTPClient.h>

#define USE_SERIAL Serial

ESP8266WiFiMulti WiFiMulti;

void setup() {

  USE_SERIAL.begin(115200);
  // USE_SERIAL.setDebugOutput(true);

  USE_SERIAL.println();
  USE_SERIAL.println();
  USE_SERIAL.println();

  for (uint8_t t = 4; t > 0; t--) {
    USE_SERIAL.printf("[SETUP] WAIT %d...\n", t);
    USE_SERIAL.flush();
    delay(1000);
  }

  WiFi.mode(WIFI_STA);
  WiFiMulti.addAP("Love", "A850F3619D");
  //WiFiMulti.addAP("Grace 3G, "11111111");
}

void loop() {
  // wait for WiFi connection
  if ((WiFiMulti.run() == WL_CONNECTED)) {

    HTTPClient http;

    USE_SERIAL.print("[HTTP] begin...\n");
    // configure traged server and url
    //http.begin("https://192.168.1.12/test.html", "7a 9c f4 db 40 d3 62 5a 6e 21 bc 5c cc 66 c8 3e a1 45 59 38"); //HTTPS
    //http.begin("http://192.168.1.12/test.html"); //HTTP
    http.begin("http://blynk-cloud.com/c2700ca3f8fa4bb9b03d8d6c778a8f40/project"); //HTTP

    USE_SERIAL.print("[HTTP] GET...\n");
    // start connection and send HTTP header
    int httpCode = http.GET();

    // httpCode will be negative on error
    if (httpCode > 0) {
      // HTTP header has been send and Server response header has been handled
      USE_SERIAL.printf("[HTTP] GET... code: %d\n", httpCode);

      // file found at server
      if (httpCode == HTTP_CODE_OK) {
        String payload = http.getString();
        USE_SERIAL.println(payload);
      }
    } else {
      USE_SERIAL.printf("[HTTP] GET... failed, error: %s\n", http.errorToString(httpCode).c_str());
    }

    http.end();
  }

  delay(10000);
}

Here is the Serial debug output from that Example sketch:

SDK:2.2.1(cfd48f3)/Core:2.4.2/lwIP:2.0.3(STABLE-2_0_3_RELEASE/glue:arduino-2.4.1-13-g163bb82)/BearSSL:6d1cefc



[SETUP] WAIT 4...
scandone
state: 0 -> 2 (b0)
state: 2 -> 3 (0)
state: 3 -> 2 (7a0)
[SETUP] WAIT 3...
state: 2 -> 0 (4)
reconnect
wifi evt: 1
STA disconnect: 202
scandone
state: 0 -> 2 (b0)
state: 2 -> 3 (0)
state: 3 -> 5 (10)
add 0
aid 1

connected with Grace 3G, channel 6
dhcp client start...
cnt 
wifi evt: 0
ip:192.168.43.213,mask:255.255.255.0,gw:192.168.43.1
wifi evt: 3
[SETUP] WAIT 2...
[SETUP] WAIT 1...
[WIFI][APlistAdd] add SSID: Grace 3G
[HTTP] begin...
[HTTP-Client][begin] url: http://blynk-cloud.com/c2700ca3f8fa4bb9b03d8d6c778a8f40/project
[HTTP-Client][begin] host: blynk-cloud.com port: 80 url: /c2700ca3f8fa4bb9b03d8d6c778a8f40/project
[HTTP] GET...
[hostByName] request IP for: blynk-cloud.com
[hostByName] Host: blynk-cloud.com IP: 45.55.96.146
:ref 1
[HTTP-Client] connected to blynk-cloud.com:80
[HTTP-Client] sending request header
-----
GET /c2700ca3f8fa4bb9b03d8d6c778a8f40/project HTTP/1.1
Host: blynk-cloud.com
User-Agent: ESP8266HTTPClient
Connection: close
Accept-Encoding: identity;q=1,chunked;q=0.1,*;q=0

-----
:wr 182 182 0
:wrc 182 182 0
:ack 182
:rn 536
[HTTP-Client][handleHeaderResponse] RX: 'HTTP/1.1 200 OK'
[HTTP-Client][handleHeaderResponse] RX: 'content-type: application/json;charset=utf-8'
[HTTP-Client][handleHeaderResponse] RX: 'access-control-allow-origin: *'
[HTTP-Client][handleHeaderResponse] RX: 'content-length: 1658'
[HTTP-Client][handleHeaderResponse] RX: 'connection: close'
[HTTP-Client][handleHeaderResponse] RX: ''
[HTTP-Client][handleHeaderResponse] code: 200
[HTTP-Client][handleHeaderResponse] size: 1658
[HTTP] GET... code: 200
:c0 1, 536
:rn 536
:rch 536, 536
:c 1, 536, 1072
:c0 1, 536
:rn 188
:rcl
:abort
:c0 1, 188
[HTTP-Client][writeToStreamDataBlock] connection closed or file end (written: 1658).
[HTTP-Client][end] tcp is closed
{"id":478616176,"parentId":-1,"isPreview":false,"name":"Washing Machine Aces","createdAt":1550243820511,"updatedAt":1553605720648,"widgets":[{"type":"LED","id":57718,"x":3,"y":3,"color":600084223,"width":1,"height":1,"tabId":0,"label":"washing machine power","isDefaultColor":true,"deviceId":0,"pinType":"VIRTUAL","pin":0,"pwmMode":false,"rangeMappingOn":false,"min":0.0,"max":0.0,"value":"0"},{"type":"TERMINAL","id":61856,"x":0,"y":0,"color":255,"width":8,"height":3,"tabId":0,"label":"Type 88  Then Send To Start","isDefaultColor":true,"deviceId":0,"pinType":"VIRTUAL","pin":1,"pwmMode":false,"rangeMappingOn":false,"min":0.0,"max":0.0,"autoScrollOn":true,"terminalInputOn":true,"textLightOn":true,"attachNewLine":false},{"type":"NOTIFICATION","id":99445,"x":0,"y":3,"color":600084223,"width":2,"height":1,"tabId":0,"isDefaultColor":true,"androidTokens":{"3aa1bab8731f139a":"e7Aqm0MxDYI:APA91bEwtGaKv8PXHF8A5K5c_RXvuRUHQfUiTtODOxn8HPYSG1X8JiDd3GedbKd2tDurl63bC5HXLdsbHlk-q3Jxa2IywCyojB-MhVF3QeQwfyGAr5zFi3UVqMsKq-DZg0P0NcdI7voS","d59ea18322402a4f":"dBF3CiPZGKA:APA91bHiIeR5ztQhKQCv7Qlae6jkntYoSRnXrp3uJ3S676WUHyOaDoj_rqQBUkrJMXuGXTa695FwBLYOdENaPIYQmgsrSjhnANcI9ZvYd-lYer_v8pfw4FT9FxNcABUyf9GPc-XTf9GN"},"notifyWhenOffline":true,"notifyWhenOfflineIgnorePeriod":0,"priority":"normal","soundUri":"content://settings/system/notification_sound"}],"devices":[{"id":0,"name":"washing machine ","boardType":"ESP8266","vendor":"washing machine,"connectionType":"WI_FI","isUserIcon":false}],"theme":"Blynk","keepScreenOn":false,"isAppConnectedOn":false,"isNotificationsOff":false,"isShared":false,"isActive":true,"widgetBackgroundOn":false,"color":0,"isDefaultColor":true}
[HTTP-Client][end] tcp is closed
:ur 1
:del

I see that when I try to connect via the tethered wifi, blynk-cloud doesn’t authenticate, Im pretty sure that the TCP/IP side is OK

Patrick

Gunner · March 26, 2019, 9:57pm

Not quite sure about your setup… this “extra” phone is ment ONLY as a WiFi Hotspot? Just for the devices, or also for running the App… or do you use a separate phone on a seperate cell account for the App?

You might be running into some form of port blocking from the Cell provider (the App wants port 9443, the hardware typically wants 8080)

And the App/Device connectivity to the server has no Geo-DNS issue, but the API method still does… not clear if you are using both or not.

A browser generally only cares about port 80… so not necessarily a good overall port test.

patrickiot · March 27, 2019, 5:52am

Hi Gunner, Thanks for taking a look!
This issue is only related to the device side of Blynk (NodeMCU connecting to Blynk-cloud). The Smartphone is simply a wifi router allowing the NodeMCU to connect to the internet.
P

patrickiot · March 27, 2019, 6:15am

Hi,

Here is where it stops working:

6 seconds after my device sends the token, the IP connection is closed:…

[49152] Connecting to blynk-cloud.com:8080
[hostByName] request IP for: blynk-cloud.com
[hostByName] Host: blynk-cloud.com IP: 45.55.96.146
:ur 1
:del
:ref 1
[49703] <[02|00|01|00] c2700ca3f8fa4bb9b03d8d6c778a8f40
:wr 37 37 0
:wrc 37 37 0
:ack 37
[55705] Login timeout
:close

Gunner · March 27, 2019, 6:19am

I honestly have no idea… but I do see that you are using a slightly older Blynk library version. Things constantly change with Blynk, and many of those changes do require current versions or everything (Library 0.6.1 as of this post)

What is generating this data?.. I am unfamiliar with seeing anything like it, and do not see any code in your Blynk sketch that is generating it… besides, with debug enabled it should be prefixed by the millis count if coming from the library/code.

patrickiot · March 27, 2019, 6:27am

Hey,
Yes this data is from the Arduino IDE>Tools>Debug Level>HTTP_CLIENT.
It shows the TCP/IP Debug messages.
I am trying to see what :ur 1 and :del mean, some of these messages are from ClientContext.h

PeteKnight · March 27, 2019, 8:49am

That’s quite an old version of the ESP core.

Pete.

patrickiot · March 27, 2019, 1:19pm

I tested telnet from my PC to 45.55.96.146:80 and 45.55.96.146:8080 via the tethered WIFI/3G smartphone, both made an IP connection OK. But I didn’t pass any data, so if my ISP is blocking, its happening after a connection is made?

patrickiot · March 27, 2019, 2:12pm

I tested the 80 and 8080 ports using
http://portquiz.net/
Both work on the Tethered WIF/3g Smartphone.

patrickiot · March 27, 2019, 5:07pm

Hi, Thanks for your comment.
So I tried
SDK:3.0.0-dev(c0f7b44)/Core:2.5.0=20500000/lwIP:STABLE-2_1_2_RELEASE/glue:1.1/BearSSL:6778687
But the sadly, the issue is still with me!
P

patrickiot · March 28, 2019, 10:45am

Today I tried the Blynk Rest API test console at:
https://blynkapi.docs.apiary.io/#reference/0/send-push-notification/notify?console=1

whilst connected to the internet on my PC via the tethered WIFI smartphone and I was able to do a POST to trigger a notification to my Blynk application.

My Issue must be related to Blynk for ESP8266. BlynkProtocol.h perhaps??
P

PeteKnight · March 28, 2019, 11:01am

I don’t think you can draw that conclusion, just based on your ability to make an API call from your PC via your tethered smartphone.

Pete.

patrickiot · March 29, 2019, 9:17am

My mobile internet provider doesn’t like the Blynk’s binary login protocol TCP PSH packet login packets! (but is OK with HTTP to ports 80 and 8080)
OK I setup my own blynk server and tried to connect to it from the WAN with the tethered WIFI smartphone.
Result: atfer the TCP 3-way handshake, the ESP nornally sends a PSH-flagged packet to the Blynk server with the Auth token as payload, which I assume is the login from the hardware to the server.
When I do this via the tethered smartphone wifi, either: the packet never leaves the ESP, or it leaves and is dropped/lost by the mobile ISP (ISP Firwall?), Anyway, that kills the TCP connection as my ESP send a FIN after waiting around 10 seconds.
So yes I think it maybe time to try another mobile ISP/SIM.

Or… is there another way to login to Blynk-cloud perhaps?

patrickiot · April 1, 2019, 9:07am

Vodacom South Africa 3G data connection, is blocking Blynk-cloud (PSH flagged) TCP/IP login binary-payload packets when my NodeMCU attempts to connect via WIFI tethered smartphone.
I have no Idea why they would block/drop these, all other types of data such as HTTP, MQTT seems to pass through without issue.
After extensive testing and searching around, I tested using a SIM card from a IOT sim card provider based in Germany which issues global data-roaming sim card for M2M/IOT applications.
I have yet to test the other South African cellular providers (MTN, Cell C etc).
I did request an unrestricted APN from Vodacom SA, and they send me confirmation of that and I changed the APN settings as directed.
I would be very interested to hear from anyone else who has experienced this issue from GPRS/3G/LTE providers around the world.
Confirmed: no issue with Blynk-cloud or Blynk for ESP.
Thanks Bylnk for an excellent contribution to IOT.
Thanks Gunner and Pete Knight for your insights.

patrickiot · April 3, 2019, 1:28pm

Tested my setup using the Sakari-mobiwire tethered feature/smartphone with:
Telkom Mobile (8ta) SIM card.
It works!
So yes,
Vodacom data APN is not working for Blynk-cloud login.

Digits · July 23, 2019, 11:43am

Hi
I have the same issue
and yes I also use Vodacom.
Funny thing is it worked for a day and then nothing.
I will get a different sim from a different network provider and will test it again
any recommendations of network providers?

regards

Paul