How to loop test LoRa communication with my RAK7243

Issue:I need to loop test LoRa comm. from my module to the RAK7243

Setup: NiceFR 1276 LoRa module

Server: None

Details: I’m building a tester for my LoRa based system that use RAK gateway and I want to basically test LoRa communication (Rx\Tx) between the module and the gateway at the manufacture factory without the need to communicate with the server.
Can you please suggest how can I do this?

One option could be to use the built-in chirpstack server, though you’d need to fulfill all the requirements of LoRaWAN, such as registering the details of a device in the server and having the device under test transmit a valid frame count within that - you can’t really keep sending packet framecount zero over and over again.

Or else write your own program (python is a good choice) that speaks the Semtech UDP protocol of the classic packet forwarder.

A test where you can determine (or at least know) the particulars of the test packets being transmitted could also be run with a node-type radio as the tester. What the gateway radio offers is flexibility of receiving packets on any of 8 frequencies at an unknown spreading factor - a flexibility key to implementing actual LoRaWAN over the air. But depending on the automatation/instrumentation of your factory test, you could potentially turn a modified copy of your product into the the test rig to exchange known raw packets with the DUT.

Thank you for your answer.
I would like to try the first option you suggested.
I have also a RAK7268 WisGate Edge Lite 2 GW.
I tried to follow this video but I did not fully understand how to configure the built-in server. Where is the NS Key? Is there a more detailed description of how to configure this?