You tcpdump output looks like the Packet Forwarder is sending to localhost:1700, however this doesn’t confirm that LoRa Gateway Bridge is running on your gateway.
[root@Wirgrid_0b031311 /root]# ps w |grep lora-gateway-bridge
1667 root 2552 S grep lora-gateway-bridge
This indicates that the lora-gateway-bridge binary is not running. I believe what you are seeing is the grep process.