How many 802.11 NULL packets should send an esp8266 while doing nothing?

[adolfocobo]

Hello to all,
I have just joined these forum because I'm struggling with a connectivity problem with all my esp8266. I am using arduino esp8266 core firmware, but I think that the problem is related to the esp8266 SDK. There are some open threads in the github issues forum with some people having this connectivity problem: the esp8266 loss connectivity, mainly due to not replying to ARP requests.
I have been monitoring my WiFi network, with two WiFi routers and 10+ esp8266 devices connected, they loss http, mqtt, ping ... connectivity from time to time randomly, and in fact, do not respond to ARP requests in a random fashion.
While debugging the WiFi traffic with Wireshark, I have noticed that the ESP8266 are generating a HUGE amount of 802.11 null packets (no data). All devices send these packets from time to time to the WiFi AP, as a "keep alive" for the network, but my esp8266s are sending up to 20 packets per second, continously. I think that this is wrong, or at least, useless, and could be related to this connectivity problem. Other devices on my network (some tablets, mobile phones, two PCs ...) only send one null packet every many seconds. Incidentally, I have an ESP32 which send one null packet every 210 seconds, exactly.
The generation of these null packets starts a few seconds after reboot, no matter which arduino software or SDK version I put in the modules, and it happens with both WiFi routers and ALL (10+) esp8266 modules I have.
Is this behaviour the intended behaviour? what is the point of so many null packets?
Thanks in advance,
Adolfo.

[Her Mary]

There is a new ESP8266 SDK V2.2 released https://github.com/espressif/ESP8266_NONOS_SDK/releases, have you tried it?
Mine sends null packet every 10 seconds, I think it is fine.. Maybe you should try to set sleep mode 0 first.

Code: Select all

wifi_set_sleep_type(NONE_SLEEP_T);