I recently bought the UD-3900 to handle a new Dell UltraSharp U3415W PXF79 34-Inch monitor with its hdmi connection.
I am using this as a docking station with the following:
HP ProBook 640 G1 Notebook
Plantronics 85619-02 Blackwire USB Headset
Multiple times during the day, the monitor goes dark and I lose my VPN connection. 10 to 15 seconds later, the display comes back and my VPN then tries to reconnect.