A couple of weeks ago I built a NAT router/gateway/firewall with a RockPro64 running NetBSD 10.1 and using NPF. After some frustration I started to better understand NPF and had a lot of fun making this work. So for at least a week, this RockPro64 has been idling along, routing packets galore. Tonight, my wife was streaming a video from some proprietary service, watching a graduation ceremony. There wasn't anything else significant happening on our LAN. Suddenly NAT wasn't forwarding packets anymore. Everything else was working except LAN devices could not see the WAN. All 6 CPUs on the RockPro64 were at idle and RAM usage was low. Restarting NPF didn't solve the problem, as expected. Removing and re-initialising the WAN interface didn't help. The only thing that helped was rebooting the RockPro64.
What could cause this, or how could I have determined what caused it?
