Unexpected result with the GSM module A6

Question

I have a GSM A6 module, like this one.

I'm going to use an Arduino Nano as a bridge to communicate with it, I have an external power source (since I read that this module can consume up to 2A at its maximum consumption) (this power supply shares the GND with the module and the Arduino) and I upload the following code in the Nano:

#include <SoftwareSerial.h>

SoftwareSerial mySerial(10, 11);

void setup()
{
  //Begin serial communication with Arduino and Arduino IDE (Serial Monitor)
  Serial.begin(9600);

  //Begin serial communication with Arduino and A6
  mySerial.begin(115200);

  Serial.println("Initializing...");
  delay(1000);


}

void loop()
{
  updateSerial();
}

void updateSerial()
{
  delay(500);
  while (Serial.available()) 
  {
    mySerial.write(Serial.read());//Forward what Serial received to Software Serial Port
  }
  while(mySerial.available()) 
  {
    Serial.write(mySerial.read());//Forward what Software Serial received to Serial Port
  }
}

I set the baud rate at 115200 of my SoftwareSerial port (connected to 10 and 11 pins on the ArduinoNano) because (even if the module says that it has auto-detect speed hability) doesn't work if I set the speed at 9600 (or any other), and I modified the SoftwareSerial library for expand the buffer from 64k to 512k (trying to solve this problem) following this page instructions (also: NICE WORK in this page!!!).

And it works ... it works relatively well, I mean: The AT commands to test (according to the datasheet itself) are AT and ATI (in one I recieve "AT /r OK" and the last one give some usefull information like the OS and other things), and they work, only they do not show me the same answer always, I leave screenshots:

As you can see, the answers are not always exact, there is some garbage characters, and I need them to be exact, because my idea is to create a kind of alarm, in which the Arduino (One, Nano or Mega) sends and receives AT commands. I worked with the SIM900 module before and always received the same answer when I sent an AT command.

So... any help?!

Answer 1

Apparently the SoftwareSerial library have some limitations, so I change the baudrate communication in the moduel ussing this sentence:

AT+IPR=9600

And change the code that I upload to the Nano, changing the baudrate speed in the declaration, from:

mySerial.begin(115200);

to

mySerial.begin(9600);

And now all is well :D