Has anyone tried using this code: https://github.com/bokse001/dual_chan_pkt_fwd/tree/dual_chan_pkt_fwd_up_down ont their Dragino Lora GPS hat? It says it can allow downlink on the hat and can be compatible with TTN. Here is the blog by the developer too: https://hansboksem.wordpress.com/2017/01/23/the-things-network-dual-channel-updownlink-gateway/