Newer Asus routers use the IP: 192.168.1.2, so try this if 192.168.1.1 does not work.
On the newer firmware there is a much easier way.
At the "Status" window, showed towards the end you can simply click on the "PC" logo or similar (the pic next to where it shows the ip of the device) and you can change its name AND IP there.
You can type in the ip you want and click the lock button and wait a few secs.
Well i hope this helps someone save a couple of seconds :)