Problema con controllo scheda relè da web

Ciao a tutti volevo sottoporvi ad un problema in quanto mi sta dando numerosi problemi.
Allora ho una scheda relè costruita da me con 6 relè che accendono un led. La mia idea è quella di controllare i singoli relè quindi accendere i led da pagina web usando arduino.
Lo sketch usato da me funziona fino a 4 relè poi quando vado ad aggiungere l'utilizzo di un quinto relè smette di funzionare. credo sia un problema di interazione tra html e arduino..volevo sapere come posso risolvere. Ecco il mio sketch
grazie

#include <SPI.h>
#include <Ethernet.h> 
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte ip[] = { 192, 168, 1, 252 };
EthernetServer server(80);
String readString;
byte out_1 = 2;
byte out_2 = 3;
byte out_3 = 4;
byte out_4 = 5;
//byte out_5 = 6;

void setup()
{ 
  Ethernet.begin(mac, ip);
  pinMode(out_1, OUTPUT);
  pinMode(out_2, OUTPUT);
  pinMode(out_3, OUTPUT); 
  pinMode(out_4, OUTPUT);
  //pinMode(out_5, OUTPUT);    
 // Serial.begin(9600);           
}
 
void loop(){
 
 EthernetClient  client = server.available();
 
  if (client) {
    boolean currentLineIsBlank = true;
   
    while (client.connected()) {
      if (client.available()) { 
        char c = client.read();
        readString.concat(c);   
        if (c == '\n' && currentLineIsBlank) {
          //Serial.print(readString);
               
        if(readString.indexOf("on_1") > 0) digitalWrite(out_1, HIGH);        
        if(readString.indexOf("off_1") > 0) digitalWrite(out_1, LOW);          
        if(readString.indexOf("on_2") > 0) digitalWrite(out_2, HIGH);        
        if(readString.indexOf("off_2") > 0) digitalWrite(out_2, LOW);          
        if(readString.indexOf("on_3") > 0) digitalWrite(out_3, HIGH);        
        if(readString.indexOf("off_3") > 0) digitalWrite(out_3, LOW); 
        if(readString.indexOf("on_4") > 0) digitalWrite(out_4, HIGH);        
        if(readString.indexOf("off_4") > 0) digitalWrite(out_4, LOW);
       //if(readString.indexOf("on_5") > 0) digitalWrite(out_5, HIGH);        
       // if(readString.indexOf("off_5") > 0) digitalWrite(out_5, LOW);
         
        //  PAGINA HTML      
        client.println("HTTP/1.1 200 OK");
        client.println("Content-Type: text/html");
        client.println();
        client.print("<html><head><title>ARDUINO Controllo WEB</title><meta http-equiv='Content-Type' content='text/html; charset=iso-8859-1' ></head><body>");
        client.print("

");
       
        client.print("<span>STATO LUCE 1 </span>");
        if (digitalRead(out_1)== true) client.print("<input disabled=\"disabled\" maxLength=\"50\" size=\"12\" value=\"ON\" STYLE=\"background-color:#00FF00\"/>");  
        else client.print("<input disabled=\"disabled\" maxLength=\"50\" size=\"12\" value=\"OFF\" STYLE=\"background-color:#C0C0C0\"/>");
        client.print("<p><p/>");   
        client.print("<input type=\"button\" style=\"width:120px; height:80px\" value=\"On\" onclick =\" location.href='/?on_1'\">");
        client.print("<input type=\"button\" style=\"width:120px; height:80px\" value=\"Off\" onclick =\" location.href='/?off_1'\">");                   
        client.print("<p><p/>");
        
        client.print("<span>STATO LUCE 2 </span>");       
        if (digitalRead(out_2)== true) client.print("<input disabled=\"disabled\" maxLength=\"50\" size=\"12\" value=\"ON\" STYLE=\"background-color:#00FF00\"/>");  
        else client.print("<input disabled=\"disabled\" maxLength=\"50\" size=\"12\" value=\"OFF\" STYLE=\"background-color:#C0C0C0\"/>");       
        client.print("<p><p/>"); 
        client.print("<input type=\"button\" style=\"width:120px; height:80px\" value=\"On\" onclick =\" location.href='/?on_2'\">");
        client.print("<input type=\"button\" style=\"width:120px; height:80px\" value=\"Off\" onclick =\" location.href='/?off_2'\">");
        client.print("<p><p/>");
        
        client.print("<span>STATO LUCE 3 </span>");
        if (digitalRead(out_3)== true) client.print("<input disabled=\"disabled\" maxLength=\"50\" size=\"12\" value=\"ON\" STYLE=\"background-color:#00FF00\"/>");  
        else client.print("<input disabled=\"disabled\" maxLength=\"50\" size=\"12\" value=\"OFF\" STYLE=\"background-color:#C0C0C0\"/>");
        client.print("<p><p/>");
        client.print("<input type=\"button\" style=\"width:120px; height:80px\" value=\"On\" onclick =\" location.href='/?on_3'\">");
        client.print("<input type=\"button\" style=\"width:120px; height:80px\" value=\"Off\" onclick =\" location.href='/?off_3'\">");        
        client.print("<p><p/>");
        
        client.print("<span>STATO LUCE 4 </span>");
        if (digitalRead(out_4)== true) client.print("<input disabled=\"disabled\" maxLength=\"50\" size=\"12\" value=\"ON\" STYLE=\"background-color:#00FF00\"/>");  
        else client.print("<input disabled=\"disabled\" maxLength=\"50\" size=\"12\" value=\"OFF\" STYLE=\"background-color:#C0C0C0\"/>");
        client.print("<p><p/>");
        client.print("<input type=\"button\" style=\"width:120px; height:80px\" value=\"On\" onclick =\" location.href='/?on_4'\">");
        client.print("<input type=\"button\" style=\"width:120px; height:80px\" value=\"Off\" onclick =\" location.href='/?off_4'\">");        
        client.print("<p><p/>");
        
        /*client.print("<span>STATO LUCE 5 </span>");
        if (digitalRead(out_5)== true) client.print("<input disabled=\"disabled\" maxLength=\"50\" size=\"12\" value=\"ON\" STYLE=\"background-color:#00FF00\"/>");  
        else client.print("<input disabled=\"disabled\" maxLength=\"50\" size=\"12\" value=\"OFF\" STYLE=\"background-color:#C0C0C0\"/>");
        client.print("<p><p/>");
        client.print("<input type=\"button\" style=\"width:120px; height:80px\" value=\"On\" onclick =\" location.href='/?on_5'\">");
        client.print("<input type=\"button\" style=\"width:120px; height:80px\" value=\"Off\" onclick =\" location.href='/?off_5'\">");*/
        client.print("<p><p/>");
        
        client.print("</body></html>");
         
        readString="";
        
        delay(1);
        client.flush();
        client.stop(); 
        }
      }
    }
  }
}

Moderator edit:
</mark> <mark>[code]</mark> <mark>

</mark> <mark>[/code]</mark> <mark>
tags added.

On the Ethernet shield I believe pin 5 is used by the SD card, try picking a different pin

Sullo scudo Ethernet credo pin 5 è utilizzato dalla scheda SD, provare a selezionare un diverso pin
Scusate se il mio (Bing Translator's) italiano non è buona

On the Ethernet shield I believe pin 5 is used by the SD card, try picking a different pin

Nope. 4, 10, 11, 12, and 13 are the only pins it uses (besides ground).

PaulS:

On the Ethernet shield I believe pin 5 is used by the SD card, try picking a different pin

Nope. 4, 10, 11, 12, and 13 are the only pins it uses (besides ground).

My mistake, I was looking at the schematic which labels that header from 1-8, still could cause an issue as he's using it at the moment

@marcoan cross-posted to the Italiano :: Software section. Please post replies there.