Really big data loss

Hello, I have really big dataloss when transmitting data over lora. I use Heltec Wireless stick (V2) and HT-M00 gateway and most of my uplinks doesn’t get to the lora server (loriot) even not to the gateway (the led doesn’t blink and the tx and rx counters stay the same). This is weird, because join requests work perfectly and device joins everytime in 1-3 attempts. Do you know where this problem could lie on? I use modified uplinkDataHandle example.

#include "LoRaWan_APP.h"

/* OTAA para*/
uint8_t devEui[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
uint8_t appEui[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
uint8_t appKey[] = {  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

/* ABP para*/
uint8_t nwkSKey[] = { 0x15, 0xb1, 0xd0, 0xef, 0xa4, 0x63, 0xdf, 0xbe, 0x3d, 0x11, 0x18, 0x1e, 0x1e, 0xc7, 0xda,0x85 };
uint8_t appSKey[] = { 0xd7, 0x2c, 0x78, 0x75, 0x8c, 0xdc, 0xca, 0xbf, 0x55, 0xee, 0x4a, 0x77, 0x8d, 0x16, 0xef,0x67 };
uint32_t devAddr =  ( uint32_t )0x007e6ae1;

/*LoraWan channelsmask, default channels 0-7*/ 
uint16_t userChannelsMask[6]={ 0x00FF,0x0000,0x0000,0x0000,0x0000,0x0000 };

/*LoraWan region, select in arduino IDE tools*/
LoRaMacRegion_t loraWanRegion = ACTIVE_REGION;

/*LoraWan Class, Class A and Class C are supported*/
DeviceClass_t  loraWanClass = CLASS_C;

/*the application data transmission duty cycle.  value in [ms].*/
uint32_t appTxDutyCycle = 60000;

/*OTAA or ABP*/
bool overTheAirActivation = true;

/*ADR enable*/
bool loraWanAdr = true;

/* Indicates if the node is sending confirmed or unconfirmed messages */
bool isTxConfirmed = true;

/* Application port */
uint8_t appPort = 2;
/*!
* Number of trials to transmit the frame, if the LoRaMAC layer did not
* receive an acknowledgment. The MAC performs a datarate adaptation,
* according to the LoRaWAN Specification V1.0.2, chapter 18.4, according
* to the following table:
*
* Transmission nb | Data Rate
* ----------------|-----------
* 1 (first)       | DR
* 2               | DR
* 3               | max(DR-1,0)
* 4               | max(DR-1,0)
* 5               | max(DR-2,0)
* 6               | max(DR-2,0)
* 7               | max(DR-3,0)
* 8               | max(DR-3,0)
*
* Note, that if NbTrials is set to 1 or 2, the MAC will not decrease
* the datarate, in case the LoRaMAC layer did not receive an acknowledgment
*/
uint8_t confirmedNbTrials = 8;

#define LEDPin 25  //LED light
void app(uint8_t data)
 {
    // lora_printf("data:%d\r\n",data);
   switch(data)
     {
    case 49:
    {
      pinMode(LEDPin,OUTPUT);
      digitalWrite(LEDPin, HIGH);
      break;
    }
    case 50:
    {
      pinMode(LEDPin,OUTPUT);
      digitalWrite(LEDPin, LOW);
      break;
    }
    case 51:
    {
      break;
    }
    default:
    {
      break;
    }
     }
 }

/* Prepares the payload of the frame */
static void prepareTxFrame( uint8_t port )
{
  /*appData size is LORAWAN_APP_DATA_MAX_SIZE which is defined in "commissioning.h".
  *appDataSize max value is LORAWAN_APP_DATA_MAX_SIZE.
  *if enabled AT, don't modify LORAWAN_APP_DATA_MAX_SIZE, it may cause system hanging or failure.
  *if disabled AT, LORAWAN_APP_DATA_MAX_SIZE can be modified, the max value is reference to lorawan region and SF.
  *for example, if use REGION_CN470, 
  *the max value for different DR can be found in MaxPayloadOfDatarateCN470 refer to DataratesCN470 and BandwidthsCN470 in "RegionCN470.h".
  */
    Serial.println("Preparint TX frame!");
    appDataSize = 4;
    appData[0] = 0x00;
    appData[1] = 0x01;
    appData[2] = 0x02;
    appData[3] = 0x03;
}

//downlink data handle function example
void downLinkDataHandle(McpsIndication_t *mcpsIndication)
{
  Serial.println("Received downlink");
  Serial.printf("+REV DATA:%s,RXSIZE %d,PORT %d\r\n",mcpsIndication->RxSlot?"RXWIN2":"RXWIN1",mcpsIndication->BufferSize,mcpsIndication->Port);
  Serial.print("+REV DATA:");
  app(mcpsIndication->Buffer[0]);
  for(uint8_t i=0;i<mcpsIndication->BufferSize;i++)
  {
    Serial.printf("%02X",mcpsIndication->Buffer[i]);
  }
  Serial.println();
  uint32_t color=mcpsIndication->Buffer[0]<<16|mcpsIndication->Buffer[1]<<8|mcpsIndication->Buffer[2];
#if(LoraWan_RGB==1)
  turnOnRGB(color,5000);
  turnOffRGB();
#endif
}

void setup() {
  Serial.begin(115200);
  while (!Serial);
  Mcu.begin();
  deviceState = DEVICE_STATE_INIT;
}

void loop()
{
  switch( deviceState )
  {
    case DEVICE_STATE_INIT:
    {
      Serial.println("INIT STATE");
#if(LORAWAN_DEVEUI_AUTO)
      LoRaWAN.generateDeveuiByChipID();
#endif
      LoRaWAN.init(loraWanClass,loraWanRegion);
      break;
    }
    case DEVICE_STATE_JOIN:
    {
      Serial.println("JOIN STATE");
      LoRaWAN.join();
      break;
    }
    case DEVICE_STATE_SEND:
    {
      Serial.println("SEND STATE");
      prepareTxFrame( appPort );
      LoRaWAN.send();
      deviceState = DEVICE_STATE_CYCLE;
      break;
    }
    case DEVICE_STATE_CYCLE:
    {
      Serial.println("CYCLE STATE");
      // Schedule next packet transmission
      txDutyCycleTime = appTxDutyCycle + randr( -APP_TX_DUTYCYCLE_RND, APP_TX_DUTYCYCLE_RND );
      LoRaWAN.cycle(txDutyCycleTime);
      deviceState = DEVICE_STATE_SLEEP;
      break;
    }
    case DEVICE_STATE_SLEEP:
    {
      LoRaWAN.sleep(loraWanClass);
      break;
    }
    default:
    {
      deviceState = DEVICE_STATE_INIT;
      break;
    }
  }
}

Here is my code with changed secrets.

Thanks in advance if somebody helps me with this problem.

HT-M00 is a dual-channel gateway, and your node is set with 8 channels.

How do I set it to work with only two channels? I suppose it has to do something with the channel mask?