Only decoders which use the latest version of the compute board will support the Wi-Fi dongles, this is due to the increased memory space available on these boards. 

To check the version of your decoder open the Menu and navigate to Info.

The mainboard/hardware and firmware versions of your decoder will be listed, after the hardware version this will show either -0 or -1,

e.g. 'Device MB/FW: 1.3-1.4-1/2.57' (on older versions 'Device HW/FW: 1.4-1/2.42') this shows a decoder with mainboard version 1.3 or 1.4, with a supported compute board and firmware revision 2.57.

If -1 is shown then the USB Wi-Fi adapter is supported. Decoders with -0, showing older hardware versions will not enable the Wi-Fi settings.