Interfacing an external application server to a network server

I am using RAK wireless 833 gateway on Raspi B+. So I have the network server running on the gateway while the application server running on the same subnet as the Raspi. I am able to add the network server on the application server on the server and also I am able to add gateway and gateway details are updated periodically. But the issue I am facing is that I am not able to gateway Lorawan frames on the application server. Neither am I able to see lorawan frames for the end-device I have added to the gateway. Could someone help me out on this?
Thanks in advance,
Emil Peter