John
That is a strange result. Perhaps if we had some additional information we could find an explanation for the behavior. Can you provide us with the IP of your PC, the IP of the router LAN, the IP of the router WAN, and the output of your traceroute?
Is it possible that the router has any kind of bridging environment that would pass the traceroute through the LAN interface? Is it possible that the router has some IP unnumbered configuration that would make ambiguous the relationship of LAN address and WAN address?
HTH
Rick
HTH
Rick