The kind of questions you are asking indicates you may not have the complete user manual, so you need to get it. This is the Support page for your EX2100: http://support.wdc.com/product/install.asp?groupid=2701&lang=en
Bookmark this and go to it to download the user manual, etc.
Now, starting at the beginning, you do not connect the 2100 to your computer. It, AND your computer must be connected to the same network; i.e. your home network, AND preferably wired to it via ethernet cable. A computer can connect either wired or wirelessly, but the 2100 NAS must connect via wired; either in the port in back of the router or into a network switch connected to the router.
When the 2100 boots up the first time it will do a lot of activity, indicated by the flashing blue LEDs, and the power light should be solid, not blinking after full startup This can take a while, so do not turn off the 2100 until ALL activity has finished, You should have a blue LED at the bottom of each drive. If any are red, you have an issue and you should restore the 2100 back to factory defaults.(using it’s DASHBOARD web page in your browser) so that all LEDs are blue, not flashing at the end of restore.
Once up and running, you will find the contents of the 2100 in Finder under Networks, not Drives. Look in via Finder to see the preset folders; e.g. Public, and the three Shared media folders where you can store your data. If you want to add media files to it from your computer, you do it with Finder as you would with any drive. (You also need to turn on DLNA media server) via Dashboard Settings tab.)
You do not need the desktop app to use the 2100; I don’t – I use it like any other drive, but the desktop app can be handy for some activities.
If your only connection of computer to network is wireless, do not expect speedy file transfers, even at 5G speed – that requires a wired connection to network.
This device really IS easy to setup. You just need to figure out what you are not doing correctly. Good luck.
Finally, your dropped connections indicate poor network connectivity; likely with wireless. One cannot connect a device like the 2100 to a poorly constructed home network. You may need some additional upgrading of your network.