Wemos D1 ESP8266, ioBroker (Raspberry Pi 3 Model B) MQTT connection failed - arduino

Question

I have a Raspberry Pi 3 Model B with ioBroker (Raspbian light Stretch) as an MQTT broker and Wemos D1 ESP 8266 with a test script. Both devices are connected to the network via Wi-Fi.
Good news:
1) I can send the MQTT signal from the phone (myMQTT apps) and it will be displayed in the ioBroker logs (the phone is connected to Wi-Fi, MicroTik).
I can send an MQTT signal from my laptop (connected to Wi-Fi or ethernet).
I can send a successful MQTT signal from a Debian virtual server (on vmware).
2) Wemos D1 successfully connects to the test server test.mosquitto.org.
The bad news:
Wemos D1 does not want to connect to ioBroker on the local network and reports the error "Attempting MQTT connection ... failed, rc = -2 try again in 5 seconds".
Why all devices except Wemos D1 ESP 8266 successfully connect to mqtt broker?
Could it be the case in the firewall?
Tell me, please, what should I do to solve this problem.
/*
Basic ESP8266 MQTT example
This sketch demonstrates the capabilities of the pubsub library in combination
with the ESP8266 board/library.
It connects to an MQTT server then:
- publishes "hello world" to the topic "outTopic" every two seconds
- subscribes to the topic "inTopic", printing out any messages
it receives. NB - it assumes the received payloads are strings not binary
- If the first character of the topic "inTopic" is an 1, switch ON the ESP Led,
else switch it off
It will reconnect to the server if the connection is lost using a blocking
reconnect function. See the 'mqtt_reconnect_nonblocking' example for how to
achieve the same result without blocking the main loop.
To install the ESP8266 board, (using Arduino 1.6.4+):
- Add the following 3rd party board manager under "File -> Preferences -> Additional Boards Manager URLs":
http://arduino.esp8266.com/stable/package_esp8266com_index.json
- Open the "Tools -> Board -> Board Manager" and click install for the ESP8266"
- Select your ESP8266 in "Tools -> Board"
*/
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
// Update these with values suitable for your network.
const char* ssid = "XXX";
const char* password = "XXX";
const char* mqtt_server = "test.mosquitto.org";
WiFiClient espClient;
PubSubClient client(espClient);
long lastMsg = 0;
char msg[50];
int value = 0;
void setup_wifi() {
delay(5000);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.mode (WIFI_STA);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.print(".");
}
randomSeed(micros());
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}
void callback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message arrived [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}
Serial.println();
// Switch on the LED if an 1 was received as first character
if ((char)payload[0] == '1') {
digitalWrite(BUILTIN_LED, LOW); // Turn the LED on (Note that LOW is the voltage level
// but actually the LED is on; this is because
// it is active low on the ESP-01)
} else {
digitalWrite(BUILTIN_LED, HIGH); // Turn the LED off by making the voltage HIGH
}
}
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Create a random client ID
String clientId = "ESP8266Client-";
clientId += String(random(0xffff), HEX);
// Attempt to connect
if (client.connect(clientId.c_str())) {
Serial.println("connected");
// Once connected, publish an announcement...
client.publish("outTopic", "hello world");
// ... and resubscribe
client.subscribe("inTopic");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(1000);
}
}
}
void setup() {
pinMode(BUILTIN_LED, OUTPUT); // Initialize the BUILTIN_LED pin as an output
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
}
void loop() {
if (!client.connected()) {
reconnect();
}
client.loop();
long now = millis();
if (now - lastMsg > 2000) {
lastMsg = now;
++value;
snprintf (msg, 50, "hello world #%ld", value);
Serial.print("Publish message: ");
Serial.println(msg);
client.publish("outTopic", msg);
}
}
Screenshots:
1) netstat -tulpn | grep LISTEN
2) ioBrocker log
3) Arduino IDE
UPDATE:
I did not find where you can change or disable listen port 1883 tcp6.
But I managed to establish a connection between the devices by replacing the Mikrotik router with Keenetic.
Now we need to figure out what's wrong with the settings of the router.

Answer 1

Your screenshot:
shows that ioBroker is listening on the IPv4 loopback interface (127.0.0.1) for ports 9000 and 9001, and on a tcp6 (IPv6) interface for ports 8081, 8082 and 1883.
That means it's only reachable via IPv4 from programs running on the same server as it, or from programs running on computers capable of speaking IPv6.
The ESP8266 is not capable of speaking IPv6.
You need to reconfigure ioBroker to listen on 0.0.0.0:mqtt so that IPv4 software can reach it.