The Sketch

The inverted LED is not a typo. GPIO2 (the D4 label) has its anode on 3.3V, so the pin sinks current to light it and LOW means on. Every ESP8266 example you copy will trip over this once.

Using It

1. Upload, then open the Serial Monitor at 115200.
2. On a phone or laptop, join the Wi-Fi network EmbedClub-Node.
3. Open http://192.168.4.1 in a browser.
4. Use the two links. The LED follows immediately.

Your phone will warn that the network has no internet and may try to switch back to mobile data. Tell it to stay connected - on Android this is usually a notification you have to tap, and on iOS it is the "Wi-Fi Assist" setting.

Things Worth Knowing

• Set a real password. softAP() with a password under 8 characters silently creates an open network instead of failing, and then anyone nearby can control the board.
• 192.168.4.1 is the default. It is not magic - it is just what the ESP AP stack hands itself. The sketch prints it so you never have to remember.
• Roughly four clients at once. The AP is meant for a phone or two, not a classroom. Beyond that, join a real router instead and serve the page there.
• This is not secure, it is just private. The page has no login, so anyone on the board’s network has full control. That is acceptable because the network is yours and short-range; it is not acceptable on a shared Wi-Fi.

Troubleshooting

• Network does not appear: the sketch did not upload, or the board is in bootloader mode. Tap reset.
• Joins, but the page never loads: the phone fell back to mobile data. Disable it and retry.
• Page loads once, then hangs: a client was left open. The client.stop() at the end of loop() is what prevents that.
• LED does the opposite of what you asked: see the note above - on-board LEDs are often wired active-low.

Where to Go Next

• Drive a relay instead of the LED to switch a real appliance.
• Add a captive portal so joining the network pops the page up on its own.
• Compare with the ThingSpeak guide when the board needs to be reachable from outside the room.