Displayport on Dell S2716DG not working but HDMI does

[lukeb28]

Setup:

- GX501VIK on Windows 10 with a Dell DA300 Thunderbolt3 dock connected over display port to my S2716DG.

 

Theory:

Windows is being dumb? I really have no idea at this point. I'd really like to get all that FPS G-Sync goodness I payed for. I got it second hand so there's no way I can even return it.

 

So far I have:

• Disabled power saving mode
• Installed Dell's drivers
• Factory reset it from the menu
• Unplugged and re-pugged the cables in every way I could think
• Having just DP plugged in
• Having DP and HDMI plugged in
• Flipped the display port cable around
• Rebooting it and my computer in every order I could think of
• Had it be the only display connected (Besides the laptop display)

 

Clues so far:

• Windows display manager shows the monitor in the arrangement window but greyed out and much smaller than the primary display.
  • When it is selected and I go to "Multiple Displays" it shows as "Disconnect this display". Changing this to "Extend" asks if I want to keep the changes (Without the monitor turning on). On accepting the changes, "Scale and layout" now shows red text that says "The display setting could not be saved". All the settings are greyed out.
• In "Advanced display settings" it simply says that Display 2 isn't active. When HDMI and DP are plugged in and I switch to DP, info about the display shows up here for a second with the disconnection windows sound, then when it disappears the windows connection sound plays.

 

I'm at my wits end, thanks for any help you can provide!

[lukeb28]

Turned out the DA300 is not an adapter but only a dock compatible with Dell Laptops for the display functionality. Using a USB C to Display port cable was what I ultimately did.