I would also like to have the latest version, I now have 3.15.06

I think your problem is not related to the SymScript version, but due to the network stack being used. You need to use a different port to control the WLAN power on the MC65 and ES400. Here is a snippet from a script we run at startup on our devices to ensure the WLAN is powered on:
// Constants representing the WLAN power states SetVar Int WLAN_POWER_FULL_ON = 0 SetVar Int WLAN_POWER_OFF     = 4 // Set the WLAN Proxy Driver port used by most devices // as the default port SetVar String strWlanPort = "WLP1:" // Get the device model SetVar String strDeviceType = GetTerminalIdent() // If the device is an MC65 or ES400, // then use the Fusion Windows CE proxy driver  If strDeviceType == "Motorola MC65"                  SetVar String strWlanPort = "WCS1:" EndIf If strDeviceType == "Motorola ES400"   SetVar String strWlanPort = "WCS1:" EndIf // Power on the WLAN device DevicePower strWlanPort WLAN_POWER_FULL_ON 1 As far as I can tell the GSM_Radio command for controlling the WWAN power will also work on the ES400 and MC65.