graphics card - How to run 3 external monitors plus laptop monitor Dell 5530 + TB16

I have a 4K touch Dell Precision 5530 laptop with Intel 630 UHD internal graphics and Nvidia P1000 discreet.

I have 2x Dell 4K U2718Q monitors and a third Dell P2213 monitor as well as a TB16 dock.

The dock has 4 monitor outputs (DP, mDP, HDMI, VGA) and states:

Triple Display (maximum
resolution)
DP + mDP+HDMI: 3 x 3840 x
2160 @ 30 Hz
NOTE: DP port at 60 Hz
is supported, but mDP
+HDMI are limited to 30
Hz for 4k

and

Quad Display (maximum
resolution)
**mDP + HDMI + DP + VGA:
3x3840 x 2160 @ 30 Hz + 1x
1920 x1200 (VGA)
NOTE: **Discrete only
mode or “Special
Graphics Mode”.
NOTE: ** Conguration supported with AMD and Nvidia in discrete-only mode or special-graphics mode. These modes are listed
in the BIOS for the following systems: Dell Precision 7510/7529/7710/7720 and will require disabling switchable graphics for
discrete-only mode or enabling special-graphics mode when Switchable is enabled. If the system does not have these options in
the BIOS, then 4 monitors are NOT supported.

Because this is from the manual for the dock, I would assume the 3 monitors/4 monitors does not include the laptop monitor. I know I can't support 4 external monitors because I don't have switchable graphics but I'm thinking I should be able to support 3 monitors however, whenever I try to plug in the 3rd monitor and extend the desktop to it (either via HDMI or VGA) it shuts off one of the other monitors.

There is also an additional HDMI port on the laptop that I could use if necessary.

Any idea how to get it working?

Answer

I speculate Dell is NOT including the laptop display in their count since they specify only 3 external (display) ports. So your model could only support laptop LCD & 2 external monitors or close lid & possibly 3 external monitors

This tech page notes 3 displays, not what type which is the point of contention. At the very least its another resource to checking wording against. Dell may be the only person who can confirm this since the wording can be open to interpretation.

--EDIT: pg34 of dock manual SEEMS to confirm: If three monitors are connected to the docking station, then the docking station will only support a maximum of two external monitors. Refer to the User Guide of your docking station for information on how to select and activate the desired monitors.