ELSYS LoRa® ERS / ERS-lite

Hi, I am using a Raspberry Pi with IMST iC880A and trying to connect Elsysy ERS into the network. I am using the semtech gateway and packet forwarder.
ABP mode is working as expected but in OTA mode its failing to complete the join processs.
In gateway logs I am getting the uplink message(join request) from the End node and also the downlink message(join complete) from network server, But Again I am getting the join request from End node.
Is any logs I will get in Elsys ERS to check whether its getting the downlink messages or not??? And how to check that logs??? is there any another way to debug on node side???