Trying to connect up to four Dell U2417H monitors to a W2100 using DP 1.2 and MST from a single port. I can get all four monitors to duplicate the first monitor, but I can't get them to extend. Dell response was that I should max out at three monitors...fine, but still can't get the third monitor to display unless it is duplicating the second monitor. Purpose is to provide a bigger workspace for design diagrams. My config is: (FirePro W2100) DP --> mDP (2417 #1) with MST set to On; (2417 #1) DP --> mDP (2417 #2) with MST set to off; (2417 #2) DP --> mDP (2417 #3). This is a WIN 10 box and the display settings show #3, but it is grayed out. Is this a configuration issue, card limitation, or something else?