Aside from the, ‘WAN Connection: Ethernet link down.’, message I was seeing in my ASUS RT-N66U system log, there are two other error messages that appear often.

miniupnpd: unsupported NAT-PMP version : 2

This message appears in my log every hour on the hour. As near as I can tell it doesn’t cause any problems with my Internet connection or general network performance. I’ve figured out it only occurs when my wife’s Mac Mini is turned on. The Mac works just fine  during and outside times the error message is being logged. Either Mac OS itself or some program she has is using UPnP in a way the ASUS router doesn’t care for. I don’t have a good answer on this outside of saying it doesn’t seem to affect much.

kernel: eth1: received packet with  own address as source address

I have two access points in my home, both with the same SSID. The first access point is the one built into the ASUS RT-N66U, the second access point is an old Netgear router with everything but the access point functionality turned off.

This error occurs when a client moves from the ASUS RT-N66U to the Netgear access point. The network is general is not affected. The client moving between the two access points will lose some packets. The packet loss isn’t noticeable unless you are looking for it.