**Below may be limited for ESP32.  Check documentation for ESP8266**

1. WiFi.setPhyMode(): Adjusting PHY mode can improve reliability.
<code>
WiFi.setPhyMode(WIFI_PHY_MODE_11B); // Set to 802.11b for better range and stability
</code>

//For ESP8266: Use WiFi.setPhyMode(WIFI_PHY_MODE_11B).
For ESP32: Use esp_wifi_set_protocol(WIFI_IF_STA, WIFI_PROTOCOL_11B).//

2. Use Long Preamble: Helps with weak signal connections.
<code>
esp_now_set_pmk((uint8_t*)"1A:FE:34:5C:67:89"); // Set primary master key
esp_now_add_peer(peerAddr, ESP_NOW_ROLE_COMBO, wifi_channel, NULL, 0);
</code>

3. Optimize Wi-Fi Settings:
<code>
WiFi.setOutputPower(20.5); // Boost transmission power
</code>

4. Acknowledge Packet Delivery: Ensures packets are received correctly.
<code>
esp_now_register_send_cb([](uint8_t *mac_addr, uint8_t sendStatus) {
  Serial.print("Send Status: ");
  Serial.println(sendStatus == 0 ? "Success" : "Failure");
});
</code>

5. ESP-NOW Broadcast: Repeatedly send data to ensure delivery.
<code>
const int attempts = 3;
for (int i = 0; i < attempts; i++) {
  esp_now_send(peerAddr, data, sizeof(data));
  delay(100); // Small delay between attempts
}
</code>