Issue description:

When connecting any amount of external displays over USB-C the display will after 30-90 Minutes turns briefly off and on, resetting all positions of the windows. After a certain amount of failures, the displays do not turn on anymore and I am forced to reconnect the cable. After reconnecting the issues appear again in about 30-90 minutes, restarting the whole issue loop.
In the brief time where the displays are off no connected USB-Devices work. For example, while phoning over an USB Headset (microphone and sound) directly connected to the laptop, the communication is not possible.

Machine details:

Fresh installed and updated Windows 10, Pro (2004) x64, where only the latest drivers from the Lenovo L390 Yoga Page are installed and double checked with Lenovo Systems Update, that did not find any missing drivers updates

• Machine type: 20NUS01W00
• BIOS Version/Date: Lenovo R10ET46W (1.31)
• Intel(R) UHD Graphics 620 Driver Version: 26.20.100.7811
• USB Type-C driver utility GUI version 1.0.2.21
• ThinkPad USB-C Dock Gen2 (40AS0090EU) with 1.0.3.03241 driver and Firmware: 1.0.6.06161
• For more details check the attached HTML that got created by the Lenovo Diagnostic Tool
• I ran the long Diagnostic Tool Test and no mistakes were found on the hardware level. Results are attached
• Windows Event Viewer logs, Intel System Support Utility logs and dxdiag logs are attached

Setup I want to run:

Since the following is the setup I want to work with, I returned most of the test equipment:

• Lenovo L390 Yoga only connected to the dock
• Lenovo USB-C Dock Gen2 (40AS0090EU) - connecting to it Ethernet, USB mouse/keyboard/headset
• Windows 10
• 2x 1920*1080@60hz Monitors (remember issue also occurs with only one monitor connected)

So far, I tested:

• The issue has been observed with two different USB-C hubs from Amazon, one USB-C to HDMI adapter (Anker) and the ThinkPad USB-C Dock Gen2
• The hubs/docking station had only one monitor connected (no USB or ethernet devices) over DisplayPort or HDMI (1920*1080@60hz) and the issue keeps happening
• The issue persists with three different monitors and different HDMI/DisplayPort cables
• The issue persists on both of the laptops USB-C ports
• The issue does NOT occur with another laptop (HP)
• The issue does NOT occur with one monitor connected directly to the HDMI port of the Lenovo L390 Yoga
• The issue does NOT occur when booting from an USB-Stick with Ubuntu 20.04 LTS
• The issue persists on a fresh installed Windows 2004 without Internet access, installing only the Intel(R) UHD Graphics 620 26.20.100.7811 driver + docking station driver and deactivating every other device in the device manager that has a missing driver
• The docking station/hub does not work without the Intel UHD Graphics driver
• Following Intel UHD Graphics drivers have been tested and the issue still persists
• 26.20.100.8476
• 26.20.100.8581 (latest beta driver)
• 26.20.100.8190 (test pending)
• 26.20.100.7323 (test pending)
• Issue also happened with BIOS Version 1.30, other BIOS Versions have NOT been tested
• The BIOS settings have been reset. Behaviour also happens when changing in BIOS changing the display priority setting from HDMI to USB-C
• I can get a total of 4 Full HD monitors (3 external+laptop screen) working, but no matter the amount of monitors connected, the issue appears after some time
• I checked all manuals and technical specifications and this should be supported by all my devices (this is also why I briefly tested 4 monitors)
• No under-/over volting/clocking has been ever done
• Since owning the laptop this issue has occurred
• The laptop is in a physical perfect condition, no drops/water damage
• The laptop is properly cooled with a cooler pad and temperatures do not rise above 60 degrees
• The issue occurs on every physical location, so weird magnetic disturbance is happening
• There is no screensaver causing this – the Windows installation is on stock settings

--> From all the tests above mentioned, I conclude that the issue has to be with Windows and/or the Intel Graphics driver, since it has been working flawless on Ubuntu, which excludes a hardware defect of the Lenovo laptop. The test with another laptop also proves that nothing is broken with my monitors/cables/hubs.

Closing thoughts:

Please let me know what else can be tested and ideally how to solve the bug. Let me also know if I should attach more logs.
I really need this to be working and it feels embarrassing that a Systems Engineer can fix servers but not his own work machine.
I have considered sending the device to Lenovo. Warranty expired in February but I still have half a year of Gewährleistung ("light warranty" in Germany)

 

PS: I am posting this now as well on some other forums, so do not wonder if you find duplicate posts on Google.

Today a DisplayPort to USB-C cable arrived and it works perfectly with one monitor (just like the HDMI-in port of the laptop would). The issues reappear when trying to connect a second monitor though.
Under the BIOS display settings I can choose between prioritizing USB-C or HDMI. According to the settings description both connectors can not work simultaneous. When testing that limitation rendered to be true - it was impossible for me to get two monitors working at all when using both USB-C and HDMI. One would simply not turn on at all.

Since the laptop has two equal (un-)functional USB-C connectors I used one to directly connect my main monitor (DisplayPort to USB-C) and the second monitor to the dock (tested both DisplayPort to DisplayPort and HDMI to HDMI). In this scenario only the second monitor turns in random intervals briefly off and comes back. It seems more stable to me because it happens less frequent, less screen off time and to recover functionality a reconnect of the cables was not necessary yet. But using this as a daily driver is too nerve breaking.

Additionally I tested a fresh installation of Windows 10 1909 with four different Intel Graphics Driver versions and the issue persisted. I do not plan on testing any older Windows version.
I also just finished testing two different brands of RAM and the issue persists. I tested using one stick (8GB) in any of the both slots and repeated it with the second (different) brand of RAM.

Lastly I increased in the BIOS the RAM for the GPU from 256 MB to 512 MB and it did not fix the issue. I expected though the available RAM to drop from 15.8 GB to 15.5 GB which did not happen. The amount for hardware reserved RAM has not changed after applying the setting (242 MB). Could this indicate something?

I have the same problem with my ThinkPad T480 and my single monitor DELL U3419W (connected over HDMI). All my drivers are up to date and hardware scan shows no problems. Long time I have used my monitor directly connected to da laptop without dock (over USB-C) and I have not notice any problems. Now in addition to the problem explained above, some time immediately after the wake up from the sleep, the speakers of the monitor start to produce silent and rhythmic knocking sound, more unbelievable thing is that when that happens, the setting menu controlled from the monitors buttons stop working properly (huge lag appear). Restarting of the monitor (power on/off or HDMI reconnection) doesn't solve the problem! Exceptionally strange for me is that that is fixed by restarting my Laptop (Windows 10 - up to date).

This issue (monitors randomly disconnecting and reconnecting) has been plaguing the Intel HD Graphics drivers for a long, long time now. I first saw this issue myself with DVI monitor connected to a 4th gen D54250WYH NUC (the team blew off the report, blaming it on my use of a KVM, which was "out of POR"). Here we are, 6 generation later, discussing the same issue continuing to occur.

krogerfeed

Thankyou Caleigh.

I have read about that driver bug in another forum, but I'm not absolutely sure that the issue is the same!?

1. My laptop have additional discrete Display adapter Nvidia GeForce MX 150.
2. That problem is observed with the docking station only.

I'm do not know if the interface have relation to the problem. Until buying my Dock I have used DP over USB-C interface (my monitor have USB-C port). Probably I will buy a DP cable and will check the system behavior.