Downlink not working


I’m running Class A device with ABP AS923.

I manage to see the uplink data that is sent by my device. However, after sending Downlink using Chirpstack UI, the downlink is not executed and I received ACK False error message. I’ve configured the RX2 as shown below. Any other configuration that i missed?

Hello everyone!
I got the same problem in AS923.
Is there a particular configuration for this frequency plan in order to receive correctly downlink packets?
Thank you!