Downlink to Lopy

[Harish kumar]

Hello everyone,
I am using lopy as a repeater and Arduino as a device. So Arduino sends data to server, I am using TTN gateway. I am okay with the uplink part. Now I am trying to send downlink to Arduino, but I need my repeater to listen the downlink, I don't know how to do that. Because the uplink and downlink are done with the same frequency in TTN. So when I give the frequency in lopy, it gets only data from device rather than receiving downlink from server.
So could anyone help me here to do in first step ?
What are the parameters can I add in my program ?
And what program should I use in my lopy repeater ?

Thank you so much in Advance.

[bmarkus]

@harish-kumar Is it a 'Class-A' device? RX window timing can be an issue.