you could also go into your router and look at the dhcp tables and try some of the addresses listed there. I had the same problem when i purchased mine used and they weren't set to static ip addresses so i looked at the dhcp table and typed in a couple of the addresses till i found it, think i got it on the second attempt Good Luck
unfortunatly a lot of routers when the ip is static (for ex. in the standard config of the s1, 192.168.1.99) don't show on the dhcp page the device.