Taken from http://damsteen.nl/blog/how-to-use-a-serial-connection-to-your-netgear-readynas as it always seems to be down
It is possible to connect to the command-line interface of your Netgear ReadyNAS using a serial connection. I have seen a very old blog post on the internet describing how to connect via serial to a Infrant ReadyNAS NV but it wasn't very clear how to connect to a Netgear ReadyNAS NVX Pioneer Edition, which I have. I guess I'm not the only one who wants to connect to their ReadyNAS, so I'm sharing my knowlegde here :)
The obvious advantages of a serial connection to your ReadyNAS is that you can experiment with network settings without the fear of rendering your NAS inaccessible. I believe it is also possible to recover the firmware in the event an update fails, although I haven't tried this myself.
Requirements