How do I troubleshoot an internal interface

[BinarySpike]

I'm new to BSD. I have an OpenBSD box acting as a firewall and dhcp server connected to a Linksys N-wireless router configured as an access point/switch.

About once a day the internal interface (nfe0) will seem to drop and my internet will go down. I cannot ping the firewall but from the OpenBSD machine I can ping the router and broadcast. The strange thing is, the latency is +5000ms. If I perform a "ifconfig nfe0 down & ifconfig nfe0 up" the connection will restore itself and all is fine.

I checked everything in /var/log/ but could not find anything timestamp'd near when the problem occurred. I've tried disabling pf and the problem persists. I'm thinking that I have a bad cable or port that is causing the connection to drop to 10/half but I don't know how to check that, or if that would even cause high latency!

So my real question is, how can I effectively troubleshoot my internal interface?

Thanks,

Nathan