We tried many SDKs including lastest 3.x, found that, if we set the esp8266 into ap or sta+ap mode with an hidden SSID, other STA is very hard to connect the AP suucessfully, often give response "+CWJAP:3" for an example if using another esp8266 module to connect it. Very occationally it would succeed.
If we enable the wifi event callback by wifi_set_event_handler_cb() in th ap module and check the
Once the other stas is trying to connect the AP, there is expected log-print under the event.
What might be the cause, and how to locate and fix?