Every uplink gets a downlink

Hello, guys.

I´m using a setup with AtMega644 + HopeRF RFM95 + LMIC 4.1.1, connecting in OTAA mode to the Everynet network in Brazil.

For what I read in the LMIC documentation, all the hardware is compatible, so I assume the problem is in the firmware.

The point is that everytime the device sends an uplink message, it gets a downlink message. These downlink messages looks all the same, with the payload “A0UBAHEDBf8AAQMFAABBBAAFCGjijA==” (attached print). Besides that, it looks like the device does not recognize the payload, once monitoring it in serial port, the datalen = 0.

Does anyone have any idea on what to do?

Thanks in advance.