How do you know it's not using your router for IE?
I suggest that you hit this link on your WM5 to confirm your IP
http://text.dslreports.com/mspeed?jisok=1
1) Turn off your WiFi, hit the link, note your IP
2) Turn ON your WiFi, give it a minute to marinate then hit that link again
-If you have the same IP then yes, it's not using your router.
-If it responds with a different IP (namely your router's external ip) then it IS working.