Setting up Join server on Separate machine

I am using RAK833 module working with raspberry Pi as a LoRa gateway. I actually wanted to set up Application server and network server on the gateway and the join server on a separate machine(Ubuntu virtual machine) in the same network as the gateway. Is it possible to do that way? Can someone help me out with this? Thanks in advance.

Yes this is possible. Please see the join_server configuration section in the loraserver.toml configuration. For details on the Join Server API that you must implement, please see the LoRaWAN Backend Interfaces Specification.

Thanks brocaar for the reply. I installed lora-app-server on ubuntu VM and I changed the join_server IP in loraserver.toml to the IP address of the VM. I was also able to add the gateway as well as the end-device to the app server on VM. But what I observed from the LoRaWAN frames was that the device sends join request to the gateway, but the gateway never accepts the request. While at the same time, when I do the same steps with lora-app-server installed on the gateway and the join_server IP address changed to localhost, it accepts the join request from the device. Please help me out by letting me know what exactly I am doing wrong.