Sorry, my bad. It is clearly a gateway log.
Apr 03 19:23:57 DEBUG TSF:MSG:READ,3-3-255,s=255,c=3,t=7,pt=0,l=0,sg=0: Apr 03 19:23:57 DEBUG TSF:MSG:BC Apr 03 19:23:57 DEBUG TSF:MSG:FPAR REQ,ID=3 Apr 03 19:23:57 DEBUG TSF:PNG:SEND,TO=0 Apr 03 19:23:57 DEBUG TSF:CKU:OK Apr 03 19:23:57 DEBUG TSF:MSG:GWL OK Apr 03 19:23:58 DEBUG !TSF:MSG:SEND,0-0-3-3,s=255,c=3,t=8,pt=1,l=1,sg=0,ft=0,st=NACK:0
The first line here shows that the gateway received a message from node 3.
The message is a Find Parent request, which means node 3 is asking for the gateway.
The last line is the gateway sending a response. The ! before TSF and the st=NACK means that the gateway sent the message, but the gateway did not receive acknowledgement from the node that the node received the reply.
The most common cause is unstable power supply. What capacitor(s) are you using? (On the Raspberry and on the node). How is the nrf powered on the node?
If you haven't already, see https://forum.mysensors.org/topic/666/debug-faq-and-how-ask-for-help/ for the most common problems and how to troubleshoot them efficiently.