We have had OpenBSD running for a couple of months now. Recently though, ever few weeks our OpenBSD server (which is running 4.9 which we use as a firewall/VPN server), it stops pushing internet traffic to our clients on the network. We can ping 188.8.131.52 and resolve google.com just fine but when it comes to actually browsing there, it just doesn't do anything. Oddly enough a reboot fixes it.
What logs should I be looking at to try and track down what might be causing this?