I'm trying to send data from my esp to my arduino using serial using the following codes :

esp :

server.on("/drive",HTTP_GET, handleDrive);
void handleDrive() 
{
    server.send(200,"text/html", "Drive!");
    String sendToArduino = "";
    for (int i=0;i<server.args();i++) 
    {
   sendToArduino = sendToArduino+server.argName(i)+"="+sendToArduino.arg(i)+"&";
    }
    Serial.println(sendToArduino);
}

and on arduino :

if (esp8266.available()) 
{
   String  readString="";
   while (esp8266.available()) 
   {
     delay(2); 
     char c = esp8266.read();  
     readString += c;
   }
}

but when i send data from esp to arduino i get it with "noise"

Ex : "variable1=1234" i recive it on arduino "variab@e=12" What can i make to make sure that what i send is same in arduino ?

I'm trying to send data from my esp to my arduino using serial using the following codes :

esp :

server.on("/drive",HTTP_GET, handleDrive);
void handleDrive() 
{
    server.send(200,"text/html", "Drive!");
    String sendToArduino = "";
    for (int i=0;i<server.args();i++) 
    {
   sendToArduino = sendToArduino+server.argName(i)+"="+sendToArduino.arg(i)+"&";
    }
    Serial.println(sendToArduino);
}

and on arduino :

Serial.begin(9600);
esp8266.begin(115200);


if (esp8266.available()) 
{
   String  readString="";
   while (esp8266.available()) 
   {
     delay(2); 
     char c = esp8266.read();  
     readString += c;
   }
}

but when i send data from esp to arduino i get it with "noise"

Ex : "variable1=1234" i recive it on arduino "variab@e=12" What can i make to make sure that what i send is same in arduino ?