If esp8266 cannot connect to wifi at any reason, the system crashes sporadically

[urmel79]

• sporadic system crashes especially when WiFi is not connected
• OTA updates do not work and also lead to system crash and reboot

[urmel79]

[bug] external interrupts conflict with WiFi connection attempts or OTA updates and lead to sporadic crashes!
[fix (workaround)] disable external GPIO interrupts temporarily

void connectToWifi() {
  Serial.println("Connecting to Wi-Fi...");
  WiFi.mode(WIFI_STA);  // client mode

  // [bug] external interrupts conflict with wifi connection attempts and
  // ota updates and lead to sporadic crashes!
  // [fix (workaround)] disable external interrupts temporarily
  // reference https://www.mikrocontroller.net/topic/460256#5573848
  ETS_GPIO_INTR_DISABLE();
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);

  // enable external interrupts again
  ETS_GPIO_INTR_ENABLE();
}

reference https://www.mikrocontroller.net/topic/460256#5573848