Lose MQTT Connection after 15-30 minutes - wifi

Question

I am currently having a problem with my ESP8266 establishing a stable connection to my mosquitto MQTT broker.
I have moved house and am therefore using a different network.
In the previous network, my ESP ran stably and I had no problems at all. The MQTTserver run on a Raspberry PI 4.
In the new network, as already mentioned, it breaks off every 15-30 minutes (no fixed length of time).
The code is of course adapted to the new network and the IP of the broker.
The code I use is probably the generally known code for connecting to the MQTT server.
I only added some I/O Ports.
Since the code worked without problems in the old network, I first thought that the WLAN connection was failing.
So in the loop I inserted the reestablishment with the WLAN.
But this is running stably:
Attempting MQTT connection...failed, rc=-2 try again in 5 seconds
Attempting MQTT connection...failed, rc=-2 try again in 5 seconds
Connecting to Vodafone-947E
.....
WiFi connected
IP address:
192.168.0.52
Attempting MQTT connection...failed, rc=-2 try again in 5 seconds
Attempting MQTT connection...failed, rc=-2 try again in 5 seconds
..............
Can it be that my new router simply interrupts the connection after some time? Otherwise, I don't understand what the problem could be.
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <Wire.h>
//----------------------------------------------------------------------------------------------------------------------
#define wifi_ssid "xxxxxxx"
#define wifi_password "xxxxxxxxx"
#define mqtt_server "192.168.0.xxx"
//----------------------------------------------------------------------------------------------------------------------
WiFiClient espClient;
PubSubClient client(espClient);
bool status;
const int OutputPin2 = 12;
const int ResetPin = 4;
int ResetCounter =0;
//----------------------------------------------------------------------------------------------------------------------
void setup() {
Serial.begin(9600);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
pinMode(OutputPin2, OUTPUT);
pinMode(ResetPin, OUTPUT);
digitalWrite(OutputPin2, HIGH);
digitalWrite(ResetPin, HIGH);
}
//----------------------------------------------------------------------------------------------------------------------
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
WiFi.begin(wifi_ssid, wifi_password);
Serial.print("Attempting MQTT connection...");
// Create a random client ID
String clientId= "ESP8266-";
clientId += String(random(0xffff), HEX);
// Attempt to connect
delay(100);
if (client.connect(clientId.c_str())) {
Serial.println("connected");
// Once connected, publish an announcement...
// ... and resubscribe
client.subscribe("esp3/LED");
} else {
ResetCounter++;
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
Serial.println(ResetCounter);
if (ResetCounter >=5)
{
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
//digitalWrite(ResetPin, LOW);
ResetCounter =0;
}
// Wait 5 seconds before retrying
delay(5000);
}
}
}
//----------------------------------------------------------------------------------------------------------------------
void loop() {
if (!client.connected()) {
reconnect();
}
client.loop();
}
//----------------------------------------------------------------------------------------------------------------------
void setup_wifi() {
delay(10);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(wifi_ssid);
WiFi.begin(wifi_ssid, wifi_password);
while (WiFi.status() != WL_CONNECTED) {
Serial.print(".");
delay(500);
}
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}
//----------------------------------------------------------------------------------------------------------------------
void callback(char* topic, byte* message, unsigned int length) {
Serial.print("Message arrived on topic: ");
Serial.print(topic);
Serial.print(". Message: ");
String messageTemp;
for (int i = 0; i < length; i++) {
Serial.print((char)message[i]);
messageTemp += (char)message[i];
}
Serial.println();
client.subscribe ("esp3/LED");
if (strcmp(topic,"esp3/LED")) {
Serial.print("Changing output to ");
if(messageTemp == "on LED"){
Serial.println("on LED");
digitalWrite(OutputPin2, LOW); //Invertiertes Signal
delay(200);
}
else if(messageTemp == "off LED"){
Serial.println("off LED");
digitalWrite(OutputPin2, HIGH);
delay(200);
}
}
}
```

Answer 1

Fortunately, I was able to solve the problem. The reason was that the WLAN signal on the ESP8266 was simply too low. As a result, the ESP was not able to stay on the network permanently. I actually ruled this out because the router is only one room away. The problem is that many routers in the surrounding flats also transmit on the same frequency band and thus influence the signal. I bought a WLAN amplifier (of course this does not improve the situation with the signal overlapping). Now I have no more problems with disconnects from the ESP and this has been the case for 2 days.