This message was posted on behalf of Intel Corporation
Our graphics HD 4600 supports the resolutions below:
DisplayPort* 1.2 eDP*:
H-Processors: 3840 x 2160 @ 60 Hz (Ultra-HD)
U-Processors: 3200 x 2000 @ 60 Hz, 3840 x 2160 @ 30 Hz
Y-Processors: 2560 x 1600 @ 60 Hz
HDMI*: 4096 x 2304, 3840 x 2160 @ 24 Hz / 24bpp
DVI: 1920 x 1200 @ 60 Hz
So, 4K is supported by Display Port (no adapters connected). In the case of your laptop, I found the maximum resolutions supported by the display are.
15.6" diagonal LED-backlit HD8 anti-glare (1366 x 768)
15.6"diagonal LED-backlit FHD SVA anti-glare (1920 x 1080)
Laptop manufacturers customize our drivers, so the maximum resolution of the external video can be affected plus the docking station might decrease the video resolution.
I suggest you to contact Hewlett Packard and request the resolutions supported by the external video port.
Quick Reference Guide for (4th and 5th) Intel® Core™ Processor Graphics
HP ProBook 650 Notebook PC