Siemens Speedstream 6520 as a Router (Not a modem!)

Is it possible that I can use this recycled piece of Aliant (my old ISP) hardware as a wireless router. I've currently installed the new firmware on it from the Aussie site, so it's not bound by Aliant anymore.

I've currently got internet flowing through it into my pc (through 2 ethernet connections only), though I cannot seem to connect to the router. It's address should be 192.168.4.1 on my network, but I just cannot connect to it to enable wireless, getting the "Though the site seems valid, the browser was unable to establish a connection." error. Any ideas?