Thank you for contacting the Intel® Communities.
This is a known situation with Display Port.
Not being able to wake from sleep while using Display Port has been an issue for a while now.
Have you tried using a different interfase in the NUC to connect your monitor (Mini-HDMI 1.4a)?
Also, you could check this thread that has the same theme.
I have struggled for a while earlier to get HDMI to work: Bought different cables, tried other graphics drivers, upgraded BIOS etc., only to give up using HDMI. Seems to be due to Intels use of an ancient 1.4a HDMI technology. DP seems to be the least crippled way to get a display of of your alpha product, so guess I have to live with it as it is.
Hello Esteban C,
I am also having a problem with the HDMI connection not waking the monitor after a long off period, usually overnight.
My monitor is Acer T232HL using HDMI cable direct from NUC5i7RYH. Waking the monitor works fine after short periods of being off (1-2 hours), however, after long periods (8-10 hours) the monitor will not wake. The only way I have figured out to get the NUC working with the monitor is to hold the NUC power button until the computer shuts down and then reboot.
I have the NUC setup to shutdown the monitor after 5 minutes and to never go to sleep.
Edit: I have restored my system to Win 8.1 and no longer have this problem with the HDMI connection. Must be an issue with Win 10.
Thank you for that additional information about the OS.
Let me perform some tests with Windows 8.1*.
Also, in order to perform the most accurate tests, please provide me with your system configuration:
Access this link and follow the instructions, Intel® System Identification Utility
I look forward to hearing from you.
Intel System Identification Utility Reference Number: 0337 5912
Date Created: Thursday, January 7, 2016 11:26:02 AM
SYSTEM INFORMATION Computer Manufacturer Intel Corporation Computer Model NUC5i7RYB Operating System (O/S) Microsoft Windows 8.1 Professional Edition (build 9600), 64-bit Operating System Build (O/S) 9600 Operating System (version) 6.3.9600 O/S Language 0409 System RAM 16 GB .NET Framework Version CD or DVD Device System Hard Drive Overview System Total Storage Size: 697.6 GB Local Disk D:\ 465.6 GB Used space: 558.2 MB Free Space: 465.1 GB Local Disk C:\ 231.9 GB Used space: 55.3 GB Free Space: 176.6 GB Memory Detail Total Physical Memory 16 GB Available Physical Memory 12.7 GB Total Virtual Memory 2.0 GB Physical Drive 0 Maker Model ST500LM021-1KJ152 Bus Type SATA Physical Drive 1 Maker Model Samsung SSD 850 EVO M.2 250GB Bus Type SATA Internet Browser  Internet Explorer Internet Browser Version  11.0.9600.18125 GRAPHICS INFORMATION Graphics Product  Intel(R) Iris(TM) Graphics 6100 Graphics Driver Version 18.104.22.16800 3D Acceleration Yes Hardware Transform & Lighting Support Yes Video Memory 3.9 GB Vertex Shader Support 5.0 Pixel Shader Support 5.0 Microsoft DirectX* Version 11.0 Current Graphics Resolution 1920x1080 Current Color Depth 32 Bits Per Pixel MOTHERBOARD INFORMATION Manufacturer not detected Model NUC5i7RYB AA Number H73774-101 BIOS Vendor Intel Corporation BIOS Version Intel Corporation RYBDWi35.86A.0352.2015.1130.1011 BIOS Release Date System Memory 16 GB Sound Card Realtek High Definition Audio PROCESSOR INFORMATION Manufacturer Intel Model Intel(R) Core(TM) i7-5557U CPU @ 3.10GHz Intel Processor analysis tools Intel Processor analysis tools CPU Speed 3.1 GHz Link to Processor Specification Link to Processor Specification CPU Revision CPU Type 00 CPU Family 06 CPU Model 3D CPU Stepping 4 WIRED NETWORKING INFORMATION Wired Networking Product Intel(R) Ethernet Connection (3) I218-V Driver Version 22.214.171.124 Hardware IDs PCI\VEN_8086&DEV_15A3&SUBSYS_20578086&REV_03 WIRELESS NETWORKING INFORMATION Wireless Networking Product Intel(R) Dual Band Wireless-AC 7265 Driver Version 126.96.36.199 Hardware IDs PCI\VEN_8086&DEV_095A&SUBSYS_90108086&REV_59
Edit 2/28/16: I have returned to Win10 and now have to turn monitor off when not using the computer as a work-around to this problem.