Soon to be released new Dell Docks may require BIOS and driver updates on your laptop before use!

I have all the firmware/driver updates with my Dell XPS 15 9550, and still have issues with the TB15 dock. It has many issues, for example sometimes the ethernet will just cut out and it will switch to wifi for a few seconds then come back to ethernet. My mouse/keyboard dongle usually works but every now and then will just cut out and stop working for a few seconds then come back. Or worse yet is if I have an external 2.5" hdd plugged in, then every time I tax the machine even a little like playing a Youtube video, like clockwork a bunch of devices will disconnect all at once as if it doesn't have enough power to run them all at the same time.

The dock is unusable to me, I can't run a business this way with uploads randomly getting ruined, keyboard/mouse going away randomly and not being able to use usb hdd's with it. I've returned it today. Maybe I'll revisit it late in the year and see if they have figured out how to make it work.

I am in the same boat as Seattle, I have a XPS 15 9550 model with the TB15 dock.  I've reinstalled windows 10 twice from USB and updated all the drivers with the firmware updated (laptop and dock/thunderbolt controller) and still can't get the USB to stay up without the perpetual cutting in and out in device manager.  I've tried the ASMedia driver mentioned as well but that still didn't improve the situation.  Everything has been updated that I can up from the software driver list on Dell's site.  Today's latest reimage included everything as of noon today (CST).

When checking the devices in the Intel Thunderbolt utility, the cable with stay connected but the dock will continuously drop and reconnect.  The USB for the mouse and keyboard drop (no power) and will come back up several minutes later.  The dock for me is unusable in this state.

An additional issue. I can keep the external display on by not allowing the laptop to close. However, when coming out of sleep it does not activate the external monitor. You must go to the laptop monitor and switch to the external every time you wake the system up. Clearly not what you want from a dock.

Progress, I am now able to close the laptop and keep the external display on. Unfortunately it was a combination a few things and I can't tell you the exact order but I think it is dependent on the order you do these things. With the laptop screen active and the external screen connected but not active you must go into display properties and select screen 2 (the external screen) and set it as the "main screen" and apply. Once the external screen is active and the laptop screen shuts off you then need to right click on an empty part of the screen and under "Graphic Options" make sure that your external display is selected (mine was "Digital Display") and not the laptop display. Then you need to reboot. At that point I was able to close the laptop and the external display stayed on and everything worked fine. So far waking from sleep works fine and it switches right to the external display. Not claiming victory yet as I have not yet tried a "restart" or a power off/on cycle. I'll try that later when I have time.

My reply to Seattle didn't go though so let's try again.  I re-installed windows twice and have the same issues Seattle mentioned.  I've installed windows today and still have the issues from before and haven't seen any improvement.  Firmware is updated for everything as well.  This is on a Dell XPS 15 9550 with TB15 dock.

The dock is unusable right now and only provides power consistently.  I can unplug the dock and plug it back in in order to get the USB to recognize the devices for 20-30 seconds before the dock disconnects completely and won't even appear in the attached thunderbolt devices.  It seems like the dock itself needs to be power cycled to fix itself for a few moments before dying again.

TB15

XPS 15 9550 Win10 Ent 64

BIOS: 01.01.15

Chipset: 10.1.1.13

Thunderbolt Firmware: 02.11.06, A02

Thunderbolt Controller 1575: 15.3.39.1 (driver says .250 but installs as .1)

ASMedia USB3.0 eXtensible Host Controller: 1.16.29.1  (upgrade didn't work mentioned by others)

Docks/Stands: Intel ME Driver Patch for Power Management: A00

_______________

Plugging in the TB15, I get about 20 seconds of full connection, then completely cuts off like the device has been unplugged (goes hidden in device manager), No video, USB connections, or internet. It will sometimes cycle on and off like this, or just stop and not reconnect again until reseating TB cable.

...the facts, as requested...

Unfortunately it turns out that even after all of that, if the system sleeps on it's own (after the time outs that I have set in power management) when I wake it up it does not return to the external display. The system wakes up but I have to open the laptop and then switch it back to the external display. 

Hopefully Dell is working on getting this fixed.

Hi,

The XPS 9550 BIOS has been updated today to 01.01.19. It has a fix for the dock issues. If you have the 9550 please apply the updated BIOS and check if it is resolving your issues.

I updated to the 01.01,19 bios. This has not fixed the issues with the external display. It will not return to the external display when coming out of sleep whether sleep is due to power plan timeout or putting the system to sleep manually. Every time i wake the system i have to open the laptop and re-select the external display. 

Due to the significant instability and problems I have disconnected the TB15 and went back to my old setup. I'll wait a few weeks to see if Dell can get the problems resolved and try again. I really want to like this dock but unless the problems get resolved I'll have to send it back.

Yep, same issue here...  Express Service Code don't do squat!  Really helpful when trying to get updated for the product.  Ha!

Still not fully functioning - network connection drops often and other mixed results, but that's the main issue.  I'm too busy with work to keep fiddling around with it, but I will try the new BIOS update and post results when I can.  Meantime, I've just been using the Dell USB 3.0 dock I we bought along with my XPS 15.  I guess this is what we get as "early adopters!"  Love the laptop though!

Here is another mystery for the Dell folks to look into. The TB15 has both a service tag and an express service code on the bottom of the unit. Neither of them are recognized by the Dell support site?

They are - 

Service Tag - 252BM82

Express Service Code - 4659796802

You even applied the USB-C patch that Brian-Dell Liason on the forum here posted?

If that is the case then Dell has struck out 100% with fixing the problem. Before I had sent mine back it was behaving exactly like yours (connecting Ethernet made everything cycle on and off ever few seconds) and that was before any of these patches, updated firmware for the Thunderbolt Controller, BiOS updates were available.

Have you tried the asmedia driver from ASUS posted earlier (can't remember whether it was on here or Notebook Review forum). Other people have had success with that when everything else failed. Look under XPS 15 Infinity Display in Notebook Review forum.

TB15 / XPS 15 9550

all my driver versions listed a few posts ago

After running the update :

BIOS: 01.01.19

I can now get the monitors and USB to work on the dock (minus the black screen issue ill put at end)

..*IF*.. the network cable is NOT plugged in. Plugging in the network cable starts the cycling of the TB15 coming up and down with everything going down for about 20 seconds, up for about 20, back down, etc..

On that subject in the Thunderbolt Software settings (icon that shows on taskbar) > Details I have:

Software package: 15.3.39.250

Application version: 15.3.39.10

Service version: 15.3.39.7

Controller driver version: 15.3.39.1

Networking driver version: Unknown   < possible problem?

I have completely removed all the thunderbolt firmware and controller and reinstalled the newest and that Unknown still comes up.

As far as when the dock is working with no network, think Im having same issue as some others. When logging into Windows (win10 ent 64) I have to have the thunderbolt unattached or all external and laptop screens go black and never attempt to come back. Same thing when unlocking and logging back in. Have to hard shutdown, reboot with thunderbolt unplugged, log into windows, see desktop, then plug in thunderbolt.

Still unable to reach my company network, though, since hardwire network connection cant be used any other way.