would it be somehow possible to change the MQTT gateway that it accepts a second broker IP in case connection to primary is lost?

I am trying to have my setup more reliable in case something brakes.

I have basically the same setup.
BME280 powered by solar and saves for the night into a 3.7V cell.
I use a proMini 3V
In addition, I have a second temp sensor (dallas) and a rain sensor attached.
The pressure sensor is doing some calculation for forecast. Also battery monitoring to know if there is still enough energy. But the solar cells are usually enough. during winter when there is some snow it might get drained.
It is sending the values from all sensors every 180000ms (3 minutes) and then going back to sleep. Also if it starts raining, the sensor has an interrupt and sends immediately.
For charing, I use this board:
https://www.aliexpress.com/item/32230225249.html?spm=a2g0s.9042311.0.0.27424c4dbHQ48S

Running flawless since quite some time.

Here is my code - it needs cleanup but I am too lazy

// 2.4. add sun sensor and shorten to 2 min intervall

#define MY_RADIO_NRF24
#define MY_DEBUG
//fix node id = 101 Wetter Station Dach
#include <SPI.h>
#include <MySensors.h>
//#include <DHT.h>
// #include <Bounce2.h>
// #include <BH1750.h>
#include <Wire.h>
#include <DallasTemperature.h>
#include <OneWire.h>
#include <Vcc.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h> // I had to change I2C address in library for 0x76 (line 32)
//   #include <Adafruit_BMP085.h>

Adafruit_BME280 bme; // I2C

#define CHILD_ID_HUM 0
#define CHILD_ID_TEMP 1
#define CHILD_ID_PRESS 2
#define CHILD_ID_FORECAST 3
//#define CHILD_ID_LIGHT 2
// #define CHILD_ID_BARO 3
#define CHILD_ID_BTEMP 4
#define CHILD_ID_STEMP 5
#define CHILD_ID_RAIN 6
#define CHILD_ID_VOLT 7
#define SENSOR A0
#define P0 1010.6

#define DIGITAL_INPUT_RAIN_SENSOR 3
//#define HUMIDITY_SENSOR_DIGITAL_PIN 4
//#define INTERRUPT DIGITAL_INPUT_RAIN_SENSOR-2
#define COMPARE_TEMP 0 // Send temperature only if changed? 1 = Yes 0 = No

#define ONE_WIRE_BUS 8 // Pin where dallase sensor is connected 
#define MAX_ATTACHED_DS18B20 16


const char *weather[] = { "stable", "sunny", "cloudy", "unstable", "thunderstorm", "unknown" };
enum FORECAST
{
  STABLE = 0,      // "Stable Weather Pattern"
  SUNNY = 1,      // "Slowly rising Good Weather", "Clear/Sunny "
  CLOUDY = 2,     // "Slowly falling L-Pressure ", "Cloudy/Rain "
  UNSTABLE = 3,   // "Quickly rising H-Press",     "Not Stable"
  THUNDERSTORM = 4, // "Quickly falling L-Press",    "Thunderstorm"
  UNKNOWN = 5     // "Unknown (More Time needed)
};


// for forecast - untouched by me :)

  float lastPressure = -1;
  float lastTemp = -1;
  int lastForecast = -1;
  const int LAST_SAMPLES_COUNT = 5;
  unsigned long  mySleep = 180000; //180000 are 3 minutes
  float lastPressureSamples[LAST_SAMPLES_COUNT];
  // this CONVERSION_FACTOR is used to convert from Pa to kPa in forecast algorithm
  // get kPa/h be dividing hPa by 10
  #define CONVERSION_FACTOR (1.0/10.0)
  int minuteCount = 0;
  bool firstRound = true;
  // average value is used in forecast algorithm.
  float pressureAvg;
  // average after 2 hours is used as reference value for the next iteration.
  float pressureAvg2;
  float dP_dt;




//Bounce debouncer = Bounce();
boolean metric = true;
int altitude = 1500; // 741 feet above sealevel
//float lastBmpTemp = -1;
//float lastPressure = -1;
float lastHum = -1;
//float lastTemp = -1;
//int BATTERY_SENSE_PIN = A1;
int lastRainValue = -1;
int lastBatteryPcnt = 0;
int updateAll = 60;
int updateCount = 0;
uint16_t lastLux;
unsigned long SLEEP_TIME = 180000; //3 minutes

int rainCounter = 0;

float lastTemperature[MAX_ATTACHED_DS18B20];
int numSensors = 1;
bool receivedConfig = false;

float oldVolts = 0;
const float VccExpected   = 3.1;
const float VccCorrection = 3.1 / 3.1; // Measured Vcc by multimeter divided by reported Vcc
Vcc vcc(VccCorrection);
static int oldBatteryPcnt = 0;

//Adafruit_BMP085 bmp = Adafruit_BMP085();
//  BH1750 lightSensor;
//DHT dht;
//  MySensor gw;

OneWire oneWire(ONE_WIRE_BUS); // Setup a oneWire instance to communicate with any OneWire devices (not just Maxim/Dallas temperature ICs)
DallasTemperature sensors(&oneWire); // Pass the oneWire reference to Dallas Temperature.




MyMessage msgHum(CHILD_ID_HUM, V_HUM);
MyMessage msgTemp(CHILD_ID_TEMP, V_TEMP);
//MyMessage msgLux(CHILD_ID_LIGHT, V_LIGHT_LEVEL);
// MyMessage msgBtemp(CHILD_ID_BTEMP, V_TEMP);
MyMessage msgPress(CHILD_ID_PRESS, V_PRESSURE);
MyMessage msgForecast(CHILD_ID_FORECAST, V_FORECAST);
MyMessage msgRain(CHILD_ID_RAIN, V_RAIN);
MyMessage msgSunTemp(CHILD_ID_STEMP, V_TEMP);
MyMessage msgVolt(CHILD_ID_VOLT, V_VOLTAGE);

void before()
{
  // Startup up the OneWire library
  sensors.begin();
}

void setup()
{
  // requestTemperatures() will not block current thread
  sensors.setWaitForConversion(false);
  //dht.setup(HUMIDITY_SENSOR_DIGITAL_PIN);
   if (!bme.begin())
   {
    Serial.println("BME init failed!");
    while (1);
   }
  else Serial.println("BME init success!");
  
  ServerUpdate(); // for first data reading and sending to controler
  wait(2000);
  ServerUpdate();

  pinMode(DIGITAL_INPUT_RAIN_SENSOR, INPUT);
  // Activate internal pull-up
  digitalWrite(DIGITAL_INPUT_RAIN_SENSOR, HIGH);

  // use the 1.1 V internal reference
#if defined(__AVR_ATmega2560__)
  analogReference(INTERNAL1V1);
#else
  analogReference(INTERNAL);
#endif
}

void presentation()
{
  analogReference(INTERNAL);


  //     bmp.begin();
  sendSketchInfo("Weather Sensor", "2.01");
  present(CHILD_ID_HUM, S_HUM);
  present(CHILD_ID_TEMP, S_TEMP);
  present(CHILD_ID_PRESS, S_BARO);
  //  present(CHILD_ID_LIGHT, S_LIGHT_LEVEL);
  //   present(CHILD_ID_BARO, S_BARO);
  //  present(CHILD_ID_BTEMP, S_TEMP);
  present(CHILD_ID_RAIN, S_MOTION);

  present(CHILD_ID_STEMP, S_TEMP);
  present(CHILD_ID_VOLT, S_MULTIMETER);
  //pinMode(DIGITAL_INPUT_RAIN_SENSOR, INPUT);
  //      lightSensor.begin();
  metric = true;
}



void loop()
{

ServerUpdate();
  updateCount += 1;
  Serial.println("aufgewacht...");

  if (updateCount == updateAll) {
    lastTemp = -1;
    lastHum = -1;
    // lastLux = -1;
    //  lastBmpTemp = -1;
    //    lastPressure = -1;
    lastRainValue = -1;
    //   lastBatteryPcnt = -1;
    updateCount = 0;
  }

/*
  
  delay(dht.getMinimumSamplingPeriod());
  float temperature = dht.getTemperature();
  if (isnan(temperature)) {
    lastTemp = -1;
  } else if (temperature != lastTemp) {
    lastTemp = temperature;
    if (!metric) {
      temperature = temperature * 1.8 + 32.0;
    }
    send(msgTemp.set(temperature, 1));
  }
  float humidity = dht.getHumidity();
  if (isnan(humidity)) {
    lastHum = -1;
  } else if (humidity != lastHum) {
    lastHum = humidity;
    send(msgHum.set(humidity, 1));
  }

  
*/
  /*  uint16_t lux = analogRead(SENSOR);
    // Serial.println("LUX: "+ String(lux));
    if (lux != lastLux) {
        send(msgLux.set(lux));
        lastLux = lux;
    }

  */

  /*
    float pressure = bmp.readSealevelPressure(altitude) * 0.01;


    float bmptemp = bmp.readTemperature();
    if (!metric) {
    bmptemp = bmptemp * 1.8 + 32.0;
    }
    if (bmptemp != lastBmpTemp) {
    gw.send(msgBtemp.set(bmptemp,1));
    lastBmpTemp = bmptemp;
    }
    if (pressure != lastPressure) {
    gw.send(msgPressure.set(pressure, 0));
    lastPressure = pressure;
    }

  */
  int rainValue = digitalRead(DIGITAL_INPUT_RAIN_SENSOR);
  wait(100);

  if (rainValue != lastRainValue) {
    send(msgRain.set(rainValue == 0 ? 1 : 0));
    lastRainValue = rainValue;
    Serial.println("RegenWert geaendert");
  }
  else if (rainCounter >= 5) //update rain every 10 minutes
  {
    send(msgRain.set(rainValue == 0 ? 1 : 0));
    rainCounter = 1;
    //Serial.println("rainCounter > als Wert");
  }
  else
  {
    rainCounter++;
    //Serial.println("rainCounter ++" + String(rainCounter));

  }

  /*
    int sensorValue = analogRead(BATTERY_SENSE_PIN);
    float voltage= sensorValue * (5.0 / 1023.0);
    Serial.println("sens:" +String (sensorValue));
    Serial.println("V:" +String (voltage));
    int batteryPcnt = (sensorValue - batteryBasement) * batteryConstant;

    if (lastBatteryPcnt != batteryPcnt) {
    gw.sendBatteryLevel(batteryPcnt);
    lastBatteryPcnt = batteryPcnt;
    }
  */

  // Fetch temperatures from Dallas sensors
  sensors.requestTemperatures();
  // query conversion time and sleep until conversion completed
  int16_t conversionTime = sensors.millisToWaitForConversion(sensors.getResolution());
  // sleep() call can be replaced by wait() call if node need to process incoming messages (or if node is repeater)
  wait(conversionTime);

  // Read temperatures and send them to controller
  for (int i = 0; i < numSensors && i < MAX_ATTACHED_DS18B20; i++) {

    // Fetch and round temperature to one decimal
    float sunTemperature = static_cast<float>(static_cast<int>((getControllerConfig().isMetric ? sensors.getTempCByIndex(i) : sensors.getTempFByIndex(i)) * 10.)) / 10.;

    // Only send data if temperature has changed and no error
#if COMPARE_TEMP == 1
    if (lastTemperature[i] != sunTemperature && sunTemperature != -127.00 && sunTemperature != 85.00) {
#else
    if (sunTemperature != -127.00 && sunTemperature != 85.00) {
#endif

      // Send in the new temperature
      send(msgSunTemp.setSensor(5).set(sunTemperature, 1));
      // Save new temperatures for next compare
      lastTemperature[i] = sunTemperature;
    }
  }

  //Serial.println("wait...");
  //wait(5000);

  //BAtterie
  int batteryPcnt = (int)vcc.Read_Perc(VccExpected);
  float volts = (float)vcc.Read_Volts();
  int myPerc = volts * 100 / VccExpected;
  Serial.print("Battery percent: ");
  Serial.print(myPerc);
  Serial.println(" %");

  Serial.print("Volts: ");
  Serial.print(volts);
  send(msgVolt.set(volts,1));
  Serial.println(" V");
  if (oldBatteryPcnt != myPerc)
  {
    sendBatteryLevel(myPerc);
    oldBatteryPcnt = myPerc;
  }


  Serial.println("sleep now...");
  sleep(1, CHANGE, SLEEP_TIME);
  //sleep(SLEEP_TIME);


  //delay(5000);
}


void ServerUpdate() // used to read sensor data and send it to controller
{
  double T, P, H;
  T=bme.readTemperature();
  P=bme.readPressure()/100.0+52.7;
  H=bme.readHumidity();
  
    int forecast = sample(P);
      send(msgTemp.set(T, 1));
      send(msgPress.set(P, 1));
      send(msgHum.set(H,1));
      send(msgForecast.set(weather[forecast]));
      
   // unmark for debuging
      Serial.print("T = \t"); Serial.print(T, 1); Serial.print(" degC\t");
      Serial.print("P = \t"); Serial.print(P, 1); Serial.print(" mBar\t");
      Serial.print("P = \t"); Serial.print(H, 1); Serial.print(" relH\t");
      Serial.print("F = \t"); Serial.print(weather[forecast]); Serial.println(" ?");
}

float getLastPressureSamplesAverage()
{
  float lastPressureSamplesAverage = 0;
  for (int i = 0; i < LAST_SAMPLES_COUNT; i++)
  {
    lastPressureSamplesAverage += lastPressureSamples[i];
  }
  lastPressureSamplesAverage /= LAST_SAMPLES_COUNT;

  return lastPressureSamplesAverage;
}

// Algorithm found here
// http://www.freescale.com/files/sensors/doc/app_note/AN3914.pdf
// Pressure in hPa -->  forecast done by calculating kPa/h
int sample(float pressure)
{
  // Calculate the average of the last n minutes.
  int index = minuteCount % LAST_SAMPLES_COUNT;
  lastPressureSamples[index] = pressure;

  minuteCount++;
  if (minuteCount > 185)
  {
    minuteCount = 6;
  }

  if (minuteCount == 5)
  {
    pressureAvg = getLastPressureSamplesAverage();
  }
  else if (minuteCount == 35)
  {
    float lastPressureAvg = getLastPressureSamplesAverage();
    float change = (lastPressureAvg - pressureAvg) * CONVERSION_FACTOR;
    if (firstRound) // first time initial 3 hour
    {
      dP_dt = change * 2; // note this is for t = 0.5hour
    }
    else
    {
      dP_dt = change / 1.5; // divide by 1.5 as this is the difference in time from 0 value.
    }
  }
  else if (minuteCount == 65)
  {
    float lastPressureAvg = getLastPressureSamplesAverage();
    float change = (lastPressureAvg - pressureAvg) * CONVERSION_FACTOR;
    if (firstRound) //first time initial 3 hour
    {
      dP_dt = change; //note this is for t = 1 hour
    }
    else
    {
      dP_dt = change / 2; //divide by 2 as this is the difference in time from 0 value
    }
  }
  else if (minuteCount == 95)
  {
    float lastPressureAvg = getLastPressureSamplesAverage();
    float change = (lastPressureAvg - pressureAvg) * CONVERSION_FACTOR;
    if (firstRound) // first time initial 3 hour
    {
      dP_dt = change / 1.5; // note this is for t = 1.5 hour
    }
    else
    {
      dP_dt = change / 2.5; // divide by 2.5 as this is the difference in time from 0 value
    }
  }
  else if (minuteCount == 125)
  {
    float lastPressureAvg = getLastPressureSamplesAverage();
    pressureAvg2 = lastPressureAvg; // store for later use.
    float change = (lastPressureAvg - pressureAvg) * CONVERSION_FACTOR;
    if (firstRound) // first time initial 3 hour
    {
      dP_dt = change / 2; // note this is for t = 2 hour
    }
    else
    {
      dP_dt = change / 3; // divide by 3 as this is the difference in time from 0 value
    }
  }
  else if (minuteCount == 155)
  {
    float lastPressureAvg = getLastPressureSamplesAverage();
    float change = (lastPressureAvg - pressureAvg) * CONVERSION_FACTOR;
    if (firstRound) // first time initial 3 hour
    {
      dP_dt = change / 2.5; // note this is for t = 2.5 hour
    }
    else
    {
      dP_dt = change / 3.5; // divide by 3.5 as this is the difference in time from 0 value
    }
  }
  else if (minuteCount == 185)
  {
    float lastPressureAvg = getLastPressureSamplesAverage();
    float change = (lastPressureAvg - pressureAvg) * CONVERSION_FACTOR;
    if (firstRound) // first time initial 3 hour
    {
      dP_dt = change / 3; // note this is for t = 3 hour
    }
    else
    {
      dP_dt = change / 4; // divide by 4 as this is the difference in time from 0 value
    }
    pressureAvg = pressureAvg2; // Equating the pressure at 0 to the pressure at 2 hour after 3 hours have past.
    firstRound = false; // flag to let you know that this is on the past 3 hour mark. Initialized to 0 outside main loop.
  }

  int forecast = UNKNOWN;
  if (minuteCount < 35 && firstRound) //if time is less than 35 min on the first 3 hour interval.
  {
    forecast = UNKNOWN;
  }
  else if (dP_dt < (-0.25))
  {
    forecast = THUNDERSTORM;
  }
  else if (dP_dt > 0.25)
  {
    forecast = UNSTABLE;
  }
  else if ((dP_dt > (-0.25)) && (dP_dt < (-0.05)))
  {
    forecast = CLOUDY;
  }
  else if ((dP_dt > 0.05) && (dP_dt < 0.25))
  {
    forecast = SUNNY;
  }
  else if ((dP_dt > (-0.05)) && (dP_dt < 0.05))
  {
    forecast = STABLE;
  }
  else
  {
    forecast = UNKNOWN;
  }

  // uncomment when debugging
  //Serial.print(F("Forecast at minute "));
  //Serial.print(minuteCount);
  //Serial.print(F(" dP/dt = "));
  //Serial.print(dP_dt);
  //Serial.print(F("kPa/h --> "));
  //Serial.println(weather[forecast]);

  return forecast;
}

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Well I think this is a workaround because something which should work doesn't for you. I would rather try to find out why your sensor doesn't work in first place. When sharing a radio, it adds complexity rather than reducing it.

What's the issue?
I have multiple LED-strips with a motion sensor and they work quite well. However having a good power source is a must, the LED might drain quite some energy.

power issue was my 1st thought. I had that before when it wasn't good enough.
I just experienced also an issue with a gateway, I had to specify the MAC address (change to whatever you like)

#define MY_MAC_ADDRESS 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xAD

BR
SJ

@yveaux I think this was the issue.
I just found that

#define MY_MAC_ADDRESS 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xAD

will specify the MAC.
After adding it, no more issues. Changed back to same topics on both gateways, seems this is no problem.

Even the gateways received different IPs via DHCP, they had the same MAC. Haven't seen an issue in any logs.
I am not sure about long term, but short it works now. Let me see if it is a permanent fix.
Still pretty strange that I receive different IPs from my router for the same MAC.
Sometimes these are the easy fixes...

Thanks for your help!

thank you @Yveaux
I changed it. Still same issue. I do not see any in the logs now. So I have different topics, different channels. both here.
Both have different client ids, both different IP's
I am lost.
As soon as I connect the 2nd gateway to the network, turning on/off in sequence of one node works a few times, after 5/7 iterations it stops, then after a few seconds all messages appear in the gateway log, also on my mqtt-spy. So there is somewhere a hickup.
after disconnection, I can turn on/off 40-50 times and no issues at all.

looks like it is mosquitto as MQTT broker.

Can we specify the mac address? maybe there is the problem with the "cheap" network adapters...

hi @electrik
this is the log of the 2nd gateway. I am only receiving messages sent from the controller to the nodes, the temp sensors etc. on the other network are not visible on the 2nd gateway. They are both in the same room, now. So from radio perspective I think it is fine.

node 121 is the only one which should be dealt with this 2nd gateway.

If I understand it correct, for node 112 received comand to turn the lights on. The gateway says it is UNKNOWN and 112 is not reachable. So far so good.
Question is, does it also arrive on 1st gateway? what is it doing with it...
I think the "simple" fix will be changing the topic. Then it should be fine.
However still thinking that there is something odd

0;255;3;0;9;TSF:MSG:READ,121-121-0,s=1,c=1,t=0,pt=7,l=5,sg=0:25.1
0;255;3;0;9;Sending message on topic: hefti-out/121/1/1/0/0
0;255;3;0;9;TSF:MSG:READ,121-121-0,s=0,c=1,t=1,pt=7,l=5,sg=0:56.5
0;255;3;0;9;Sending message on topic: hefti-out/121/0/1/0/1
0;255;3;0;9;TSF:MSG:READ,121-121-0,s=255,c=3,t=0,pt=1,l=1,sg=0:96
0;255;3;0;9;Sending message on topic: hefti-out/121/255/3/0/0
0;255;3;0;9;Message arrived on topic: hefti-in/112/0/1/0/3
0;255;3;0;9;!TSF:MSG:SEND,0-0-112-112,s=0,c=1,t=3,pt=0,l=2,sg=0,ft=0,st=NACK:62
0;255;3;0;9;Message arrived on topic: hefti-in/113/0/1/0/3
0;255;3;0;9;!TSF:RTE:113 UNKNOWN
0;255;3;0;9;!TSF:MSG:SEND,0-0-113-113,s=0,c=1,t=3,pt=0,l=2,sg=0,ft=0,st=NACK:79
0;255;3;0;9;Message arrived on topic: hefti-in/117/0/1/1/2
0;255;3;0;9;!TSF:RTE:117 UNKNOWN
0;255;3;0;9;!TSF:MSG:SEND,0-0-117-117,s=0,c=1,t=2,pt=0,l=1,sg=0,ft=0,st=NACK:1
0;255;3;0;9;Message arrived on topic: hefti-in/102/0/1/1/2
0;255;3;0;9;!TSF:RTE:102 UNKNOWN
0;255;3;0;9;!TSF:MSG:SEND,0-0-102-102,s=0,c=1,t=2,pt=0,l=1,sg=0,ft=0,st=NACK:1
0;255;3;0;9;Message arrived on topic: hefti-in/113/0/1/0/3
0;255;3;0;9;!TSF:RTE:113 UNKNOWN
0;255;3;0;9;!TSF:MSG:SEND,0-0-113-113,s=0,c=1,t=3,pt=0,l=1,sg=0,ft=0,st=NACK:0
0;255;3;0;9;Message arrived on topic: hefti-in/112/0/1/0/3
0;255;3;0;9;!TSF:MSG:SEND,0-0-112-112,s=0,c=1,t=3,pt=0,l=1,sg=0,ft=0,st=NACK:0```

@electrik thanks.
I would hope that they are just connected to the one they can talk to (via radio), right?
Anyhow it is a bit complicated to debug them, they are in places where I cannot bring my PC.

When I uploaded the 2nd one and had the first sensor ready, I noted in the log, that also messages from other sensors appeared but mentioned something that I cannot remember but something like "ignoring message".

So this would be very strange if this is an issue as repeater nodes are all over the place and never had any issues.
I am just thinking how many people do have a similar setup with gateways on different IDs and same MQTT topic.

Will try to change the topic, then I can also get some hints from the log potentially.

Hi there!

I have one MQTT gateway. All worked very well. Then added a 2nd gateway on a different channel and in my basement. There is no radio contact between the two.
My configuration:

// Set this node's subscribe and publish topic prefix
#define MY_MQTT_PUBLISH_TOPIC_PREFIX "hefti-out"
#define MY_MQTT_SUBSCRIBE_TOPIC_PREFIX "hefti-in"

// Set MQTT client id
#define MY_MQTT_CLIENT_ID "hefti-3"

both Gateways have different client IDs, but same publish/subscribe topics.

It sometimes takes up to 30 seconds until a message is received by a sensor node (turning lights on), sometimes it is fast. turn it on/off several times, works very unpredictable.

After pulling the plug on the 2nd gateway, all works again.

Any ideas? Do I need to choose different publish/subscribe ID's for this? Or possibly QOS of the MQTT broker?

Thanks!
SJ