A little over a year ago I got the CSV-1546, which I use to connect either of my two laptops (Thinkpad X1 Carbon and HP Elitebook) to two external Dell monitors. 
It worked great for several months, and then one day stopped working completely (the monitors were no longer recognized by the computers).
I thought the device was faulty so I had it replaced with a new unit, but now, again, after several months of use the same problem appeared.

Am I doing something wrong? is there a way to safely disconnect the adapter when switching laptops that I should be aware of? Anything I should try that can fix this or to make sure it won’t happen in the future?

Thanks