wireless-helper package note added to the WiKi HERE
...or HomePlugs.Wiki said:Wi-Fi may not work in Maintenance mode, (the wireless-helper package may help), If it is not possible to telnet into the Maintenance mode use a wired LAN
If you normally use a Wi-Fi USB dongle as your network connection from the HD- or HDR-FOX, this may not work in Maintenance Mode - if not, try installing the /wireless-helper/ package. If it is still not possible to obtain a Telnet connection by Wi-Fi, use a wired LAN (or other networking which connects through the Ethernet port - e.g. HomePlug).