shouldnt need too but your router may have set limits on the amount of ip adresses it can use.
with mine i can say 1-253 possible adresses..
so if i set it to 10. only ips ending with 1 2 3 4 5 6 7 8 9 or 10 would work.. 11 wouldnt.
also when you change the xbox to manual ip through unleashx you have to set it to manual then restart then setthe ip address.
I generaly set my ip through unleasx then have xbmc use the dashboard ip.
you can check thatthe routers ip address is correct by typing
http://192.168.0.1 in to your web browser.
that should take you to your routers config page.