Arduino PubSubClient fail to connect to Mosquitto - arduino

Question

I'm trying to complete my brewing system with Arduino, Raspberry, mqtt, MySql, Php.
I want to switch from sending data via serial port to ethernet+MQTT.
When I try to publish-subscribe with PubSubClient everything goes well. But whenever I try to put the DallasTemperature begin() function it can't connect anymore to the broker.
As soon as I remove the instruction sensors.begin(); it restarts and works perfectly.
Any of you knows why the hell is acting like this?
Here the code:
#include <OneWire.h>
#include <DallasTemperature.h>
#include <SPI.h>
#include <PubSubClient.h>
#include <Ethernet.h>
#define ONE_WIRE_BUS 10
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature Sensors(&oneWire);
// Pins
const int photocellPin = 1; // the cell and 10K pulldown are connected to a1
// Variables
String lightC;
unsigned long time;
char message_buffer[100];
// Network Settings
// MAC address of ethernet shield
// Look for it on a sticket at the bottom of the shield.
// Old Arduino Ethernet Shields or clones may not have a dedicated MAC address. Set any hex values here.
byte MAC_ADDRESS[] = { 0xFE, 0xED, 0xDE, 0xAD, 0xBE, 0xED };
// IP address of MQTT server
byte MQTT_SERVER[] = { 192, 168, 2, 46 }; // 10, 192, 191, 77 { 192, 168, 1, 115 };
// Handles messages arrived on subscribed topic(s)
void callback(char* topic, byte* payload, unsigned int length)
{
Serial.print("Messaggio ricevuto [");
Serial.print(topic);
Serial.print("]");
for (int i = 0; i < length; i++) {
char receivedChar = (char)payload[i];
Serial.print(receivedChar);
}
Serial.println();
}
EthernetClient ethClient;
PubSubClient client(MQTT_SERVER, 1883, callback, ethClient);
IPAddress ip(192, 168, 2, 177);
void setup()
{
// Initilize serial link for debugging
Serial.begin(9600);
Ethernet.begin(MAC_ADDRESS, ip);
delay(2000);
// initialize the digital pin's as an output.
Serial.println("connected...");
Sensors.begin();
Serial.println("initialized..."); // Just for checking
}
void loop()
{
if (!client.connected()) {
reconnect();
}
lightC = dtostrf(analogRead(photocellPin), 5, 2, message_buffer); // TMP36 sensor calibration
Serial.println(lightC);
delay(2000);
// Publish sensor reading every X milliseconds
if (millis() > (time + 60000)) {
time = millis();
client.publish("fromarduino", (char*)lightC.c_str());
}
// MQTT client loop processing
client.loop();
}
void reconnect()
{
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Attempt to connect
if (client.connect("mb-arduino")) {
Serial.println("MQTT connected");
client.publish("fromarduino/alive", "I'm alive!");
client.subscribe("toarduino");
}
else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
It always returns error rc=-2.