Use "the things uno" to try to send information to the gateway, but result show 'no free channel'

End Devices (Nodes) Hardware
1

I try to use “the things uno” to send information to the gateway, like video shows in the ‘quick start’ [https://www.youtube.com/watch?v=rK8oJHZ9Q7U].
But when I registered the device and tried to send a message, the result was like this

-- STATUS
EUI: 0004A30B001C03xx
Battery: 3273
AppEUI: 0000000000000000
DevEUI: 0004A30B001C03xx
Data Rate: 5
RX Delay 1: 1000
RX Delay 2: 2000
-- JOIN
Model: RN2483
Version: 1.0.1
Sending: mac set deveui 0004A30B001C03xx
Sending: mac set adr off
Sending: mac set deveui 0004A30B001C03xx
Sending: mac set appeui 0000000000000000
Sending: mac set appkey 77FE7617559F77BA9D82F8F0A603F781
Sending: mac save 
Sending: mac set rx2 3 869525000
Sending: mac set ch drrange 1 0 6
Sending: mac set ch dcycle 0 799
Sending: mac set ch dcycle 1 799
Sending: mac set ch dcycle 2 799
Sending: mac set ch dcycle 3 799
Sending: mac set ch freq 3 867100000
Sending: mac set ch drrange 3 0 5
Sending: mac set ch status 3 on
Sending: mac set ch dcycle 4 799
Sending: mac set ch freq 4 867300000
Sending: mac set ch drrange 4 0 5
Sending: mac set ch status 4 on
Sending: mac set ch dcycle 5 799
Sending: mac set ch freq 5 867500000
Sending: mac set ch drrange 5 0 5
Sending: mac set ch status 5 on
Sending: mac set ch dcycle 6 799
Sending: mac set ch freq 6 867700000
Sending: mac set ch drrange 6 0 5
Sending: mac set ch status 6 on
Sending: mac set ch dcycle 7 799
Sending: mac set ch freq 7 867900000
Sending: mac set ch drrange 7 0 5
Sending: mac set ch status 7 on
Sending: mac set pwridx 1
Sending: mac set retx 7
Sending: mac set dr 5
Sending: mac join otaa 
Join not accepted: denied
Check your coverage, keys and backend status.
Sending: mac join otaa 
Join not accepted: denied
Check your coverage, keys and backend status.
Sending: mac join otaa 
Join not accepted: denied
Check your coverage, keys and backend status.
Sending: mac join otaa 
Response is not OK: no_free_ch
Send join command failed
Sending: mac join otaa 
Response is not OK: no_free_ch
Send join command failed
Sending: mac join otaa 
Response is not OK: no_free_ch
Send join command failed

The code I use is

#include <TheThingsNetwork.h>

// Set your AppEUI and AppKey
const char *appEui = "0000000000000000";
const char *appKey = "77FE7617559F77BA9D82F8F0A603F781";

#define loraSerial Serial1
#define debugSerial Serial

// Replace REPLACE_ME with TTN_FP_EU868 or TTN_FP_US915
#define freqPlan TTN_FP_EU868

TheThingsNetwork ttn(loraSerial, debugSerial, freqPlan);

  
void setup()
{
  loraSerial.begin(57600);
  debugSerial.begin(9600);

  // Wait a maximum of 10s for Serial Monitor
  while (!debugSerial && millis() < 10000)
    ;

  debugSerial.println("-- STATUS");
  ttn.showStatus();

  debugSerial.println("-- JOIN");
  ttn.join(appEui, appKey);
}

void loop()
{
  debugSerial.println("-- LOOP");

  // Prepare payload of 1 byte to indicate LED status
  byte payload[1];
  payload[0] = (digitalRead(LED_BUILTIN) == HIGH) ? 1 : 0;

  // Send it off
  ttn.sendBytes(payload, sizeof(payload));

  delay(10000);
}

The problem seems to be the duty cycle. How can I set it to transmit information successfully？

2

Please do not post your issue in multiple threads - it distracts/dilutes effort and responses.

Have you used Forum search (top right) for no_free_ch - this has come up many times over the years

Make sure not too close to GW and also in range of GW

The other thread you just posted to/resurrected is >2 years old but also included a link to one of the earlier threads (5 years old!) covering this issue a couple of posts above your!