Adding desktop to RAK7248

I am trying to add the Desktop to a RAK7248.
My initial attempt has been to install a fresh copy of the Raspberry PI system and then install the packet-forwarder. I’ve added the various additional files in the
/opt/ttn-gateway/packet_forwarder/lora_pkt_fwd directory.
The packet forwarder is receiving and forwarding messages, but it isn’t able to connect to the GPS.
Any ideas?