Replacement for the the ESP32 SimpleWiFiServer sample code to improve latency on iOS devices.

SimpleWiFiServer.ino

// Replacement for the the ESP32 SimpleWiFiServer sample code to improve latency on iOS devices.
// Cause of the delay: iOS Safari opens a speculative TCP connection before sending the real HTTP request when you tap a link.
// The fix: early-exit on a silent client.
void loop() {
  NetworkClient client = server.available();
  if (!client) return;

  // Wait briefly for the request line to arrive.
  unsigned long start = millis();
  while (!client.available() && client.connected() && millis() - start < 10) {
    delay(1);
  }

  // If the client connected but sent nothing, it's a speculative preconnect.
  // Drop it immediately — don't waste cycles parsing or responding.
  if (!client.available()) {
    client.stop();
    return;
  }

  // Read just the first line: "GET /path HTTP/1.1"
  String requestLine = client.readStringUntil('\n');
  requestLine.trim();
  Serial.print("Request line: ");
  Serial.println(requestLine);

  // Extract the path (between the two spaces).
  int firstSpace  = requestLine.indexOf(' ');
  int secondSpace = requestLine.indexOf(' ', firstSpace + 1);
  String path = (firstSpace >= 0 && secondSpace > firstSpace)
                  ? requestLine.substring(firstSpace + 1, secondSpace)
                  : "/";
  Serial.print("Path: ");
  Serial.println(path);

  if (path.endsWith("/H")) {
    digitalWrite(5, HIGH);  // GET /H turns the LED on
  }
  if (path.endsWith("/L")) {
    digitalWrite(5, LOW);  // GET /L turns the LED off
  }

  // Drain remaining request data without parsing it.
  // This is important: iOS may send body/headers we don't care about,
  // but the socket needs to be clear before we respond.
  while (client.available()) client.read();

  // Send a complete, well-formed response with explicit length and close.
  client.println("HTTP/1.1 200 OK");
  client.println("Content-type:text/html");
  client.println();

  // the content of the HTTP response follows the header:
  client.print("<meta name='viewport' content='initial-scale=1.0, width=device-width'>");
  client.print("Click <a href=\"/H\">here</a> to turn the LED on pin 5 on.<br>");
  client.print("Click <a href=\"/L\">here</a> to turn the LED on pin 5 off.<br>");
  client.println();

  client.stop();
}