Constant disconnection using cellular link

I have a disconnection every minute, I used SIM900, SIM800, M590 modules. Used cellular communication providers Beeline and Activ.
Has anyone gotten a stable connection with the server? Can I see the code?

Here is my code. Mega2560 + M590

#include <SimpleTimer.h>

#define BLYNK_PRINT Serial    // Comment this out to disable prints and save space

// Default heartbeat interval for GSM is 60
// If you want override this value, uncomment and set this option:
//#define BLYNK_HEARTBEAT 30

// Select your modem:
//#define TINY_GSM_MODEM_SIM800
//#define TINY_GSM_MODEM_SIM900
#define TINY_GSM_MODEM_M590      //сейчас работаем на M590 модуле

#include <TinyGsmClient.h>
#include <BlynkSimpleSIM800.h>

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

// Your GPRS credentials
// Leave empty, if missing user or pass
const char apn[]  = "internet";
const char user[] = "";
const char pass[] = "";

// Hardware Serial on Mega, Leonardo, Micro
#define SerialAT Serial2

SimpleTimer timer;

#define OUT_LED             4 // мониторинг наличия связи с сервером

TinyGsm modem(SerialAT);

void sendOnOff()  //эта функция выполняеться по таймеру периодически
   static int temp;

   digitalWrite(OUT_LED, HIGH);
   temp = analogRead(A0);    //датчик освещенности на улице
   digitalWrite(OUT_LED, LOW);

void setup()
  // Set console baud rate

  // Set GSM module baud rate

  pinMode(OUT_LED,  OUTPUT);

  // Restart takes quite some time
  // To skip it, call init() instead of restart()
  Serial.println("Initializing modem...");
  delay(10000);     //ждем пока модем очухается

  Blynk.begin(auth, modem, apn, user, pass);

  timer.setInterval(2000L, sendOnOff);        // 

void loop()

@russo I have moved your post into it’s own topic as you had originally posted in a thread that was over a year old.

As for your issue, while I have no experience with Cellular link and Arduino, based on other sketches I have seen with quick Google searches, 115200 BAUD seems a bit high, have you tried slowing the speeds down for the M590?

@Gunner 115200 is very fine with hardware serial ports (UART, USART…) . This was tested (NANO + SIM900). Some reconnects occurred (every hour or two, sometimes stable for up to few hours…).
Only software serial have to be limited to up to 38400 (tested with ATMEGA 328)