WiFi Stopped connecting (ESP8266)

Using Arduino IDE 1.x
3

Juraj:
your RF settings on the esp8266 flash are lost or wrong. it can happen if you erase the flash or if you upload a sketch or firmware build with different version of Espressif SDK

What RF settings?

To troubleshoot this, I downloaded the IDE to a laptop that never had the Arduino IDE installed. I installed the ESP8266 boards and ran WiFiscan.ino from the ESP8266WiFi Examples in the IDE. The scan finds my AP: "Kaywinnet (-58)". Next, I ran my WiFi_Test.ino that just connects to the WiFi. Instead of printing dots while waiting for the WiFi.status() to connect, I print WiFi.status(). Here I see a few "6 WL_DISCONNECTED" followed by "1 WL_NO_SSID_AVAIL" forever.

Here is my test sketch:

#include <ESP8266WiFi.h>                // Include the Wi-Fi library 


char ssid[] = "Kaywinnet";
const char* password = "806194xxxx";     // The password of the Wi-Fi network

void setup() {
  Serial.begin(115200);                  // Start the Serial communication to send messages to the computer
  delay(10);
  Serial.println('\n');

  WiFi.disconnect();
  delay(100);

  //Serial.setDebugOutput(true);            // Watch the connection attempts

  WiFi.begin(ssid, password);             // Connect to the network
  Serial.print("Connecting to ");
  Serial.print(ssid); Serial.println(" ...");

  while (WiFi.status() != WL_CONNECTED) { // Wait for the Wi-Fi to connect
    delay(1000);
    Serial.print(WiFi.status()); Serial.print(' ');
  }

  Serial.println('\n');
  Serial.println("Connection established!");
  Serial.print("IP address:\t");
  Serial.println(WiFi.localIP());
  Serial.println();
  WiFi.printDiag(Serial);
  Serial.println();

}

void loop() { }