ESP-NOW encrypt with ESP32 peer (Arduino 3.x): silent no-recv on SoftAP ESP8266

Summary

Encrypted ESP-NOW between ESP32 (Arduino-ESP32 3.x) and ESP8266 SoftAP fails silently (no recv on 8266) even with matching PMK/LMK, same channel, and STA joined SoftAP. Unencrypted peers work on the same setup.

Full write-up + repro sketch shapes:

https://github.com/espressif/arduino-esp32/issues/12796

ESP8266 side (fail)

esp_now_set_kok((u8*)PMK, 16);
esp_now_add_peer(tail_mac, ESP_NOW_ROLE_COMBO, 2, (u8*)LMK, 16);
// recv_cb never called for encrypted frames from ESP32

Workaround

esp_now_add_peer(tail_mac, ESP_NOW_ROLE_COMBO, 2, NULL, 0);  // no encrypt

Also document please

ESP8266 SoftAP MAC ≠ STA MAC (WiFi.softAPmacAddress() / client WiFi.BSSID() vs WiFi.macAddress()). Wrong peer MAC also looks like “ESP-NOW ready but dead.”

Asking: is encrypted ESP-NOW ESP32↔ESP8266 supported? If not, docs would save a lot of bench time.

Field notes: https://github.com/tmdrake/DRAKE_2_0_TAIL/blob/main/docs/ESPNOW_ENCRYPT_CROSS_CHIP_ISSUE.md