Debugging packet forwarding

Issue: I am setting up a RAK7271 with RAK2287 developer gateway. I seem to be able to get it connected to TTN and I can get a node joining the network and visible in TTN OK. However, I am not receiving any data packets.
Can you please point me to where to find the right logs to see what’s happening around the packet forwarder?

Setup: RPi 3 B+ with RAK7271 with RAK2287

Server: TTN

Details: Test node is Dragino DDS75-LB.