LoRa communication between Lopy4 and Heltec ESP32 V2

Hello guys, I’m trying to create a pure LoRa project using the 915MHz band between a Lopy4 (receiver) and a heltec ESP32 V2 (transmitter). I’m still learning about the settings, I just set the bandwidth and frequency setting and got some strange scenarios, I would like to share with you:

Did you notice that the sending of data is constant but the receipt is varied?

Is there a possibility to fix this problem?

I used: GitHub - Inteform/esp32-lora-library: Low-level Lora (SX127_) library for the ESP-32 IDF (Lib LoRa ESP-IDF to Heltec) and LoRa (Lopy4)

What is the time unit for time.sleep? milliseconds or seconds (i.e. is it checking every 4 milliseconds, or every second?) As perhaps it’s not checking frequently enough, or conversely, checking too fast, and the transmission isn’t complete yet?

Maybe it’s worth looking at lora.events (also documented on the pycom.io page linked), and instead checking for a LoRa.RX_PACKET_EVENT before triggering the receive function?