WiFiServer stop working after second WiFi.begin(ssid,pass)

[Vovanchik]

Right now, I am working on the failover function for WiFi connection, in other words, initiating WiFi reconnect when WiFi.status() != WL_CONNECTED. The problem is that WiFi re-connection works well, but WiFiServer stops working after reconnecting. Is it a way to restart WebServer as well with WiFi connection?

Firmware on ESP8266:

AT version:1.7.5.0(Oct  9 2021 09:26:04)
SDK version:3.0.5(b29dcd3)
compile time:Oct 15 2021 18:05:30
Bin version(Wroom 02):1.7.5

Sketch is simple:

#include <SoftwareSerial.h>
#include <WiFiEspAT.h>

SoftwareSerial EspSerial(4, 5);

WiFiServer server(80);

void setup() {
  int  baund = 9600;

  Serial.begin(9600;);
  EspSerial.begin(9600;);
  delay(1000);
  Serial.println("[INFO] --== SERIAL PORTS CONFIGURED ==--");

  WiFi.init(EspSerial,ESP_RESET_PIN);
  delay(1000);
  WiFi.reset(ESP_RESET_PIN);
  delay(1000);  
  connectToWiFi();
  Serial.println("[INFO] --== WiFi CONNECTED ==--");

  server.begin();
  Serial.println("[INFO] --== WEB SERVER STARTED ==--");

}

void loop(){
  if (millis() - timing > 5000) {
    timing = millis(); 

    if (WiFi.status() != WL_CONNECTED) {
      Serial.println("[INFO] WiFi disconnected!!!");
      connectToWiFi();

      server.end();     <---- possible Web server restart
      server.begin();  <---- possible Web server restart
    }

 }
}

void connectToWiFi(){
  statusWiFi = WiFi.status();

  while (statusWiFi != WL_CONNECTED) {
      Serial.print('.');
      statusWiFi = WiFi.begin(ssid, pass);
    }
}

[JAndrassy]

I guess it is a feature of the AT firmware. Just use server.begin() again

[Vovanchik]

I am using it loop(), but it doesn't work.

Thank you for your response. I'll create an issue in AT firmware project: https://github.com/espressif/ESP8266_NONOS_SDK.

Feel free to close this one.

[JAndrassy]

turn on debug logging so we can see the AT commands exchange

[Vovanchik]

If you have some instructions on how to turn it on, it will be awesome.

[JAndrassy]

https://github.com/JAndrassy/WiFiEspAT#logging

[Vovanchik]

Hi JAndrassy. It looks like there is a small bug in the library.

After enabling debug logging and investigation I noticed that command AT+CIPSERVER which is used to manage a server work's only when AT+CIPMUX is set to 1, which means that multiple connections are activated. Source: https://www.espressif.com/sites/default/files/documentation/4a-esp8266_at_instruction_set_en.pdf page 51.

11:05:08.585 -> esp INFO: stop server
11:05:08.622 -> esp> AT+CIPSERVER=0 ...sent
11:05:08.660 -> esp> AT+CIPSIYԂj ...ignored
11:05:08.698 -> esp> ERROR ...error
11:05:08.698 -> esp ERROR: expected OK got ERROR

11:05:08.736 -> esp INFO: begin server at port 80
11:05:08.774 -> esp> AT+CIPSERVERMAXCONN=1 ...sent
11:05:08.848 -> esp> AT+CIPSIY⸮a=99⸮1 ...ignored
11:05:08.885 -> esp> OK ...matched
11:05:08.885 -> esp> AT+CIPSERVER=1,80 ...sent
11:05:08.885 -> esp> AT+CIPSIYԊb‚j ...ignored
11:05:08.922 -> esp> ERROR ...error
11:05:08.988 -> esp ERROR: expected OK got ERROR

After code review, I noticed that AT+CIPMUX is set in utility/EspAtDrv.cpp, line 98 during WiFi.reset() or WiFi.init commands.

  if (!simpleCommand(PSTR("ATE0")) || // turn off echo. must work
      !simpleCommand(PSTR("AT+CIPMUX=1")) ||  // Enable multiple connections.                      <---- HERE
      !simpleCommand(PSTR("AT+CIPRECVMODE=1"))) // Set TCP Receive Mode - passive
    return false;

In my case, I made an HW reset of the ESP8266 module without restarting Arduino Nano.

Proposition: As for me command AT+CIPMUX=1 must be set every time when AT+CIPSERVER is called, in other words when either serverBegin (utility/EspAtDrv.cpp, line 699) or serverStop (utility/EspAtDrv.cpp, line 723) is called.

NOTE: In the current implementation, it is not obvious that WiFi.reset needs to be called to set AT+CIPMUX=1.

[JAndrassy]

the library needs all the commands sent in init() for all WiFiClient and WiFiUDP functions. I will not send all initialization commands before every command. don't reset the esp without resenting the Arduino.

[Vovanchik]

Make sense. Thank you for your response.

I found a workaround for my case with reset() function.