Hello!
I tried sending data with same device. Firstly, when I used 0000000000000003 DevEUI, 14bytes+0003 appSessionKey, 14bytes+0003 nwSessionKey and 00000003 devAddress, This device can receive the ACK. Secondly, I added to server new device with changing all address keys and EUI 0003 to 0004. Finally, I changed these address keys and eui at device and tried again. I can see the data at server and server send to ack with downlink unconfirmed frame but device can not receive ack. I do not understand what is the problem.