There is something wrong with your network or the way you are connecting to the MBL Duo. At work I have one connected to our work network and have no issues connecting or transferring data. At home I also have no issues. I have an early 2011 Mac Book Pro.
So maybe some questions are in order.
How are you actually connecting to the MBL Duo? Through AFP or SMB? If through finder, then you might want to see if you can connect via SMB (choose the connect as option).
How is your network connected? Is your DLink router connected to a Modem? What type of network topology do you have? Are you wirelessly connecting to the MBL Duo? If so, you might want to connect the Duo directly to your MBP with an Ethernet cable - That will help eliminate the wireless component.
You might also want to check your routers configuration. You could set the MBL Duo up as a static IP and assign the Google DNS servers (8.8.8.8 and 4.4.4.4) as your DNS servers. Some times service provider DNS servers don’t always resolve correctly.
