WPS fails with most new (802.11ac) access points

[dalbert2]

Basic Infos

WPS connection fails with most newer access points but work fine with older b/g/n APs.

UPDATE: the main WPS issue turned out to be lack of free memory. It turns out that a substantial (>16K) amount of free RAM is needed for WPS to succeed. I never got it working with the Belkin .ac router but it seems to work with most .ac access points as long as there's enough free RAM.

Hardware

Hardware: ESP-12F
Core Version: 2.1.0-rc2

Description

The same code works perfectly to connect via WPS with older (802.11b/g/n) access points but fails on newer (ac1900) access points even when the 5GHz radio is disabled. WPS finds the access point SSID but the negotiation to get the PSK fails. 100% failure rate with Belkin AC1900 DB (Model F9K1124V1)

Settings in IDE

Module: Generic ESP8266 Module
Flash Size: 4MB
CPU Frequency: 80Mhz
Flash Mode: qio
Flash Frequency: 40Mhz
Upload Using: SERIAL
Reset Method: nodemcu

Sketch

extern "C" {
   #include "user_interface.h"
}

LOCAL void ICACHE_FLASH_ATTR
wps_status_cb(int status)
{
   wifi_wps_disable();
   Serial.printf("\n\rwps_status_cb: ");
   switch (status) {
   case WPS_CB_ST_SUCCESS:
      Serial.printf("success!");
      wifi_station_connect();
      break;
   case WPS_CB_ST_FAILED:
      Serial.printf("failed.");
      break;
   case WPS_CB_ST_TIMEOUT:
      Serial.printf("timeout.");
      break;
   case WPS_CB_ST_WEP:
      Serial.printf("WEP: not supported.");
      break;
   case 4:
      Serial.printf("scan error.");
      break;
   default: Serial.printf("%u", status);
   }
   Serial.println();
}

void setup() {
   Serial.begin(115200);
   system_set_os_print(1);
   Serial.setDebugOutput(true);
   wifi_set_opmode(STATION_MODE);
   wifi_station_set_auto_connect(0);
   delay(5000);
   wifi_wps_disable();
   wifi_wps_enable(WPS_TYPE_PBC);
   wifi_set_wps_cb(wps_status_cb);
   wifi_wps_start();
}

void loop() {
   yield();
}

Debug Messages

wps scan
build public key start
build public key finish
f r0, wifi status: 0 phy_mode: 3
wps discover [belkin.150]
scandone
WPS: neg start
f r0, scandone
state: 0 -> 2 (b0)
state: 2 -> 3 (0)
state: 3 -> 5 (10)
add 0
aid 1
cnt
wifi_wps_disable
state: 5 -> 0 (0)
rm 0

wps_status_cb: failed.

[dalbert2]

Also fails with the example in 2.4.0 documentation (http://arduino-esp8266.readthedocs.io/en/latest/esp8266wifi/station-class.html#wps) (never gets past the while ! WL_CONNECTED loop)

#include <ESP8266WiFi.h>

void setup(void)
{
  Serial.begin(115200);
  Serial.println();

  Serial.printf("Wi-Fi mode set to WIFI_STA %s\n", WiFi.mode(WIFI_STA) ? "" : "Failed!");
  Serial.print("Begin WPS (press WPS button on your router) ... ");
  Serial.println(WiFi.beginWPSConfig() ? "Success" : "Failed");

  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print(".");
  }
  Serial.println();
  Serial.print("Connected, IP address: ");
  Serial.println(WiFi.localIP());
}

void loop() {}

The output rapidly repeats the wps discover...cnt sequence, so fast that I don't think it could actually do the key exchange. It does this until the AP WPS mode expires at which point the ESP8266 just tries to reconnect (unsuccessfully) every few seconds.

wifi_wps_enable
wps scan
build public key start
build public key finish
wps discover [belkin24]
scandone
WPS: neg start
scandone
state: 0 -> 2 (b0)
state: 2 -> 3 (0)
state: 3 -> 5 (10)
add 0
aid 1
cnt
Success
wps discover [belkin24]
state: 5 -> 0 (0)
rm 0
WPS: neg start
scandone
state: 0 -> 2 (b0)
state: 2 -> 3 (0)
state: 3 -> 5 (10)
add 0
aid 1
cnt
.wps discover [belkin24]
state: 5 -> 0 (0)
rm 0
WPS: neg start
scandone
state: 0 -> 2 (b0)
state: 2 -> 3 (0)
state: 3 -> 5 (10)
add 0
aid 1
cnt
.wps discover [belkin24]
state: 5 -> 0 (0)
rm 0
WPS: neg start
scandone
state: 0 -> 2 (b0)
state: 2 -> 3 (0)
state: 3 -> 5 (10)
add 0
aid 1
cnt

[dalbert2]

Another data-point: WPS works fine with an Asus TM-AC1900 access point, but fails with the Belkin AC1900

[Rotzbua]

Can the esp connect to the Belkin with normal pw?

[dalbert2]

Yes, this is strictly a WPS problem. The ESP receives the SSID but fails to process the key. The same code works perfectly for WPS connection with an Asus TM-AC1900 and for every 802.11b/g/n AP I've tried.  I had hoped it was a free-memory issue (the source of my original WPS problems with 802.11ac), but I've freed up a lot of RAM (more than 20K) and it still does not work with the Belkin access point.  Any ideas? Regards, Dave

…

On 12/11/2017 4:02 PM, Rotzbua wrote: Can the esp connect to the Belkin with normal pw? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#3941 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AFEbugIOL4sMRI1koXC9rTcGCBxnrTrZks5s_ZhqgaJpZM4Q8M4g>.

-- David Albert 301-728-0718 (cell)

[Rotzbua]

The esp do not support 802.11ac. Both router have a backwards compatibility for n-standard. It seems that the Belkin maybe have a different behaviour or implementation than the Asus.

First I would eliminate all link connections. So try to force the Beklin into 802.11n and 20 MHz mode, because the esp8266 do not support n-standard with 40Mhz and may have a problem with mixed mode of Belkin.
Best

[dalbert2]

I should have been clearer.  The issue is that the ESP cannot connect to the router on 2.4GHz (I know the ESP does not support 5GHz).  I have tried every setting on the Belkin AP including turning off the 5GHz radio entirely and forcing g, n, 20MHz, and 20/40MHz modes.  When the ESP attempts a WPS pairing, it sees the Belkin SSID and attempts a connection but does not receive the key and the WPS process immediately fails. Other devices (e.g. my cell phone) are able to pair with the Belkin router using WPS.

…

On 12/12/2017 4:29 AM, Rotzbua wrote: The esp do not support 802.11ac. Both router have a backwards compatibility for n-standard. It seems that the Belkin maybe have a different behaviour or implementation than the Asus. First I would eliminate all link connections. So try to force the Beklin into 802.11n and 20 MHz mode, because the esp8266 do not support n-standard with 40Mhz and may have a problem with mixed mode of Belkin. Best — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#3941 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AFEbusBr9dBMV8TmWx1zbaKeFqoT-l35ks5s_kdsgaJpZM4Q8M4g>.

-- David Albert 301-728-0718 (cell)

[shoemakersp]

You mentioned trying every setting, but I did not see security mode noted directly. Most new routers default to WPA2 only and I often have to set the 2.4 to WPA/WPA2 for "older" devices. Again, you likely tried this, but I am curious if this has been addressed. Thank you for noting this problem and sharing your results with this.

[Rotzbua]

Actually there a two WPS versions available. WPS 1.0 and 2.0. The esp doc do not mention which version or compatibility is given... Maybe this is the source of problem?

[dalbert2]

It might help if we had more information about which access points work and which don't.  So far, the Belkin AC1900 is the only AP I have not been able to get it to work with.  If anyone else is having WPS issues, I'd be grateful if you would add to this list which APs you have tested and which worked and which didn't.

[igrr]

Keeping this issue open since it can help collect more data, but please be advised that WPS is fully implemented in ESP8266 non-OS SDK. As such, it is unlikely that anything will be done to solve this issue in this project.

[devyte]

@dalbert2 I think the core has migrated to a new SDK since this was opened, and I think the new SDK includes some fixes for WPS. Please retry with latest git.
Be aware that you now have to set a menu option that disables a 4KB memory optimization in favor of WPS in the IDE.