Ethernet stability

No. This is it: No watchdog, no timeout.

/*
 
 Garage door open/closed detector.
 
  Based on Web Server by:
  
 created 18 Dec 2009
 by David A. Mellis
 modified 4 Sep 2010
 by Tom Igoe
 
 Modified by Nick Gammon
 9th Feb 2011
 
 */

#include <SPI.h>
#include <Ethernet.h>

// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {  0x90, 0xA2, 0xDA, 0x00, 0x2D, 0xA1 };

// our address
byte ip[] = { 10, 0, 0, 240 };

// the router's gateway address:
byte gateway[] = { 10, 0, 0, 1 };

// the subnet:
byte subnet[] = { 255, 255, 255, 0 };

// which pin to connect the relay to (held high by internal pullup)
#define relayPin 7

// Initialize the Ethernet server library
// with the IP address and port you want to use 
// (port 80 is default for HTTP):
Server server(80);

void setup()
{
  // start the Ethernet connection and the server:
  Ethernet.begin(mac, ip, gateway, subnet);
  server.begin();
  
    // initialize the relay pin as a input:
  pinMode(relayPin, INPUT);
  digitalWrite(relayPin, HIGH);   // set pullup resistor

}

void loop()
{
  // listen for incoming clients
  Client client = server.available();
  if (client) {
    // an http request ends with a blank line
    boolean currentLineIsBlank = true;
    while (client.connected()) {
      if (client.available()) {
        char c = client.read();
        // if you've gotten to the end of the line (received a newline
        // character) and the line is blank, the http request has ended,
        // so you can send a reply
        if (c == '\n' && currentLineIsBlank) {
          // send a standard http response header
          client.println("HTTP/1.1 200 OK");
          client.println("Content-Type: text/html");
          client.println();

          client.print ("Garage door is ");
          byte door = digitalRead(relayPin); 
          if (door == HIGH)
            client.println ("closed.");
          else
            client.println ("open.");
       
          break;
        }
        if (c == '\n') {
          // you're starting a new line
          currentLineIsBlank = true;
        } 
        else if (c != '\r') {
          // you've gotten a character on the current line
          currentLineIsBlank = false;
        }
      }
    }
    // give the web browser time to receive the data
    delay(1);
    // close the connection:
    client.stop();
  }
}