The simplest troubleshooting method would be to either test your notebook on another "n" network, or try another "n" wireless device with your router in order to find out if the problem is with the router or the notebook.
Without spending money on new equipment just for testing, you could perhaps visit a friend/neighbor and ask if you could connect your notebook to their WiFi network. They might also be amenable to trying their notebook/phone/tablet on your network to test your router.--
We can never have enough of nature.
We need to witness our own limits transgressed, and some life pasturing freely where we never wander.