when connected to a mobile via bluetooth, I cannot turn on wi-fi in samsung gear s2?

You can easily connect the Samsung Gear S2 device to a Wi-Fi network to use the Internet or share media files with other devices. However, please note that this feature is only available when the Gear S2 is not connected to the mobile device. When the Gear S2 is connected to a Mobile device via Bluetooth, the Wi-Fi network connection on the Gear S2 is no longer necessary because Gear S2 will use the data network of mobile device.