With the unit in Auto mode, it listens for the Nas Navigator software to be active on a PC on the network, and will enter sleep mode if it does not find the software. In order for this mode to function properly, the Nas Navigator software needs to be installed on every PC on your network.
If you do not wish to install the Nas Navigator software on your PCs, please flip the power switch on the back of your Linkstation to the ON position. This will leave the drive on, until you manually turn it off.
This should resolve your PCs network discovery issues.