As DNS can play a big part with your internet connection, you could also do a flush of it to clear the cache.
C:\>ipconfig /flushdns
If you still have issue after all that, try and update the router firmware, reset your router and check the MAC cloning option. I don't know if these will help but you can't be too sure of anything. has any effect as you were able to connect in the first place, but try it.