Investigating USB-C Problems on Some Dell XPS and Precision Laptops

Summary: Based on information gathered while helping Plugable customers along with feedback from Dell owners on public forums, it appears some percentage of Dell USB-C systems are exhibiting unstable USB data I/O over their USB-C port.

Update 7/14/2016 – We have had several confirmed cases where lowering the Power Output of the internal Wi-Fi adapter to 75% in Dell XPS models has helped with USB-C disconnect behavior. This has also been discussed in the Dell support forum ->

Please see our detailed instructions for lowering the Power Output and the bottom of this post here

Update 7/11/2016 – Our initial reports from customers indicate that even with the release of the latest updates from Dell applied there are still some cases where USB-C devices may not work as expected. Several customers have confirmed that enabling ‘Airplane Mode’ is an effective workaround

Update 7/7/2016 – Over the past few days Dell has released several updates for many of their Thunderbolt 3/USB-C systems, including the XPS 13 9350, XPS 15 9550, and Precision 5510. These include updates to the system BIOS, the Thunderbolt 3 driver as well as the Thunderbolt 3 NVM firmware. Please be sure to visit and use your Dell Service Tag ( to locate, download and install the latest updates for your system as a first troubleshooting step should you encounter any issues with our USB-C docking stations with a Dell system.

The BIOS updates will be under the ‘BIOS’ category, while the Thunderbolt 3 driver and NVM firmware updates will be located under the ‘Chipset’ category. Best practice is to update the BIOS first, the Thunderbolt driver second, and NVM firmware third.

Plugable recently launched two USB-C docking stations ( and and they have proven to be very popular; so much so that we’re having trouble staying in stock. Any time we launch a new product, especially one (or in this case two) that makes use of a new technology such as USB 3.1, support engineers like myself always learn a lot in the first few weeks. (For a quick synopsis of our data points, jump to the end of post.)

Plugable UD-ULTCDL Ports

Plugable UD-ULTCDL USB-C Triple Display Docking Station

The vast majority of customers reported both units worked well with many popular models of USB-C systems (we have compatibility tables on the respective product pages), which aligned with the results we observed while developing the devices. But there were of course cases where things did not. At Plugable those who help develop a product also provide the support, and in the normal course of troubleshooting certain patterns often emerge which we view as an opportunity for further investigation into various issues that might occur.

What’s been most interesting with our USB-C docks was that when things didn’t work as expected, they would do so in an extremely inconsistent manner, often manifesting with instability of attached USB devices. For example, a customer with a Dell Precision 5510 laptop was experiencing random disconnects when using one of our docks. After investigating the behavior via our handy diagnostic tool PlugDebug ( we elected to send a pretested replacement dock to rule out a hardware problem. Plugable is different from a lot of other companies in that when we send replacements they are tested at length by a human being in our lab. Despite this effort, when the customer received the replacement (which had been tested over 12 hours) the behavior was still present.

Our support engineers set out to better understand the issue. Why did the docks work great for the vast majority of customers’ XPS 9350 and 9550 systems (and Plugable’s identical in-house test systems) while a handful of other customers with the same systems were having problems, even with a known good tested replacement docking station?

We collectively scratched our heads and dug deeper. Our first focal point was nearly all of these problem reports were coming from owners of Dell Thunderbolt 3-enabled systems like the XPS 13, XPS 15 and Precision 5510. (The same chip which enables Thunderbolt 3 functionality on these systems also enables USB 3.1, which is the protocol used to communicate with our USB-C docks.)

Since Dell’s XPS lineup are among the most popular Thunderbolt 3/USB-C systems it was no surprise to see them well represented with our customers, but what was so surprising was this small percentage of systems which we knew to be compatible yet were not working as expected.

Having just launched our first Thunderbolt 3 products (, we knew very well that all Thunderbolt 3 systems were receiving frequent BIOS and Thunderbolt 3 firmware updates which dramatically help Thunderbolt 3 and USB-C stability. Yet even with these updates applied on certain systems we still saw issues in specific instances.

TBT3-DP2X Adapter

Plugable Thunderbolt 3 Dual DisplayPort Adapter

Digging deeper, we found references to similar behavior online within Dell’s support forums ( for some users of Dell’s Thunderbolt 3 and USB-C docking stations. While the thread is quite long, it does reflect similar unstable dock behavior while also indicating the common theme of the whole USB bus resetting or disconnecting and causing problems.

As official Dell comments on the thread have dropped off, customers have tried their own pragmatic approach in finding work-arounds and some (but not all) have found the behavior diminished if the laptop was run with the lid open. Others found that putting the system in ‘Airplane Mode’ to disable the internal Wi-Fi and Bluetooth adapter helped. And there’s even multiple users who report working with Dell engineering on the issue, stating that Dell is aware of the problem on some systems and working on a fix in the form of a BIOS update.

Note that Dell recently posted a BIOS update for the Dell XPS 13 9350 and the Release Notes indicated Thunderbolt 3, USB-C and Docking station fixes. Unfortunately this update was removed by Dell shortly after it was posted (

Even with our growing suspicions that some host systems were a key part of the problem, we didn’t feel certain about this until we worked through an especially tricky support case involving an XPS 15 9550 and our Triple Display Dock. In the course of troubleshooting USB disconnection issues mentioned above we again sent a pretested replacement dock to rule out a hardware problem but again the issue remained. The customer even went to the extraordinary length to have Dell replace the system, and yet the issue remained. In this case we actually sent the customer some additional Plugable USB 3.0 products an effort to isolate the behavior further. Using our UD-3900 dock with an adapter via the Dell’s USB Type-C port produced the same disconnect symptoms, but when used via the Dell’s USB Type A port it worked as expected. As our investigation continued the customer replaced his system a third time for a reason unrelated to the dock behavior, and lo and behold both our UD-3900 and our USB-C Triple Display Dock were now working properly via the Dell’s USB-C port.

So where does this leave us? While we have many test systems in our lab, we do not have an example of every model Dell system that has Thunderbolt 3 and USB-C. In our internal testing with the Dell XPS 13 9350 and Dell XPS 9550 (non-hybrid) both of our USB-C docks work well. We are hopeful based on Dell forum comments that updated system BIOS files or Thunderbolt 3 NVM firmware will be released to help with the behavior. Though we don’t know if in some cases the solution will go beyond BIOS/firmware updates and instead is indicative of a hardware problem with the host system itself.

Interestingly as we were putting the finishing touches on this post before publishing, Dell has posted a BIOS update for their Thunderbolt 3/USB-C Precision 7510 and 7710 models that indicate various Thunderbolt 3 and USB-C fixes. Our hope is that these changes will filter down through their other models in the near future.

In the meantime, if anyone encounters issues with our USB-C products and a Dell USB-C or Thunderbolt 3 system please contact us directly at and we will be happy to help. We thank all of our current and future customers for their patience and feedback as we continue to learn about the various USB-C systems and how our products interact with them.

Here are the data points we’ve gathered from customer tickets and the other public resources mentioned in this article:

  • The behavior seems to only affect a small number of systems (relatively speaking, given the popularity of Dell’s systems)
  • We have seen similar reports from owners of: Dell XPS 15 9350, Dell XPS 15 9550, and Dell Precision 5510
  • The instability primarily affects transmission of USB data packets; Alternate Mode video seems much less likely to be impacted
  • Turning on Airplane Mode can help minimize issues
  • Using the system with the lid open can help minimize issues
  • Some users report better behavior when maximizing the distance of the USB-C peripheral from the system (i.e; use all available cable length)
  • Per multiple user confirmation on the Dell thread above, Dell will be implementing a BIOS fix “soon”
  • Dell has already released, then pulled, a BIOS update for the XPS 13 9350 which indicated it contained several fixes related to USB-C and Thunderbolt 3 stability
  • Some users who installed the update before it was pulled by Dell report diminished WiFi signal strength after applying the update
  • On the Dell forums, one user reported calling Dell to troubleshoot his USB-C issues and was sent a replacement laptop that fixed the issues
  • Plugable has worked with a customer who was experiencing USB-C device instability using his XPS 15 connected to our Triple Display Dock. After replacing his docking station with a pre-tested known good unit and still having problems, the customer replaced his XPS twice(!). The second replacement XPS he received solved the issue
  • Given the impact of the factors above (Airplane Mode, distance from the PC, the BIOS update impacting WiFi, etc) it seems very possible the wireless/Bluetooth module in some systems might generating interference with the integrity of USB-C data. (Yet another reminder of the complexities of high frequency signaling!)

Instructions for lowering Power Output of the internal Wi-Fi adapter in Dell XPS

1. Open Device Manager
2. Expand the ‘Network Adapters’ category
3. Right-click on the entry for the Wi-Fi adapter and select ‘Properties’
4. From the ‘Advanced’ tab, scroll down and select ‘Power Output’ from the ‘Property’ column, and then select 75% in the ‘Value’ drop down (example screenshot below).
5. Click OK to commit the change.
6. Reboot the system

XPS 13 9350 WiFi Power Setting2

26 comments on “Investigating USB-C Problems on Some Dell XPS and Precision Laptops”

  1. Aaron Marks Reply

    I have access to many new Dell laptops and came to an identical conclusion. I believe the latest laptops Dell is shipping directly don’t exhibit this behavior, but anything purchased from a 3rd party vendor could come from older inventory. We’ve also found that Dell uses older parts often when repairing computers or replacing computers which is why repairs/replacements don’t fix the issue.

    • Gary Zeller Reply

      Thanks for the reply Aaron! Always appreciate corroborative data when working through this kind of puzzle.

      And good to hear that newer stock doesn’t seem to be affected. Here’s to hoping a solution for affected systems is close at hand, because these hiccups aside, Dell’s USB-C lineup is tough to beat.

  2. Mark Reply

    Thanks for this post. As an XPS13 and WD15 owner. It’s very nice to finally get some useful information, even if it’s not coming from Dell. Hopefully they will re-release the BIOS soon and my big expensive Dell brick might finally become useful.

    As an aside, do you really think it’s a small percentage of Dell laptops affected, or could it be that it’s a relatively small percentage of Dell thunderbolt laptop users who own usb-c docks. I’d suspect the latter.

    • Bob Boerner Bob Boerner Reply

      Thanks for the kind words, they are much appreciated.

      To your question, I think it would be quite difficult to pin down a number (and I wouldn’t want to hazard a guess) without more data. Our current data is based on helping customers when things don’t work as expected with our USB-C products, and that is a very specific window into the overall number of users.

  3. Lance Hughes Reply

    ust my two cents here. This is not only happening on Dell systems. I am using the new larger USB-C with my razer blade stealth. Both my keyboard and mous conneed are experiencing issues. The inconssistenc in this comment is actually a point to this issue. Tea lag is uuuuuuuuuuuuuuuuuuuearable and ouse only started experienciiiiiiiiiiiiiiiiiiing these issues on i moved the usb adapter from the laptop issssssssssssssssssslef to the dock.

    • Patric Neumann Reply

      Please contact us directly at if you are having problems with your Razer and one of our USB-C docking stations.

      EDIT: Just found your email.

  4. Maciej Reply

    My little contribution is, try fixing Wi-Fi to a 5ghz network. That seems to have solved a lot of problems with my xps 13 9350. There is also good article on Intel website about interference if 2.4ghz and usb connections.

    • Bob Boerner Bob Boerner Reply

      Thank you for the contribution. We have also found switching to the 5 GHz band can also help in some instances. In some cases if your wireless router doesn’t support the 5 GHz band that won’t be an option, so lowering the transmit power would be the workaround.

      Thanks again!

  5. Tom N. Reply

    I have been using a Plugable USB 2.0 display adapter connected to a Dell WD15 dock, which is connected via USB-C to a Precision 5510 running Windows 10. The display works fine, unless I move ANY Windows Store application (or Edge) to that monitor, then it typically disconnects/reconnects immediately and will randomly disconnect/reconnect afterward. I noticed that I don’t have the problem with non-store apps (Chrome, RDP), they will run all day on that screen with no problem… so I don’t know if that’s somehow a factor…

    • Bob Boerner Bob Boerner Reply

      Interesting symptoms you describe. As a quick test to isolate the behavior, if you disconnect the Dell WD15 dock temporarily (we want to remove it from the equation) and connect the Plugable adapter directly to one of the Precision 5510’s integrated USB Type-A ports does the behavior change?

      • Tom N. Reply

        So, I tried as you suggested and I didn’t experience any problems when the Plugable adapter is connected directly. BUT, this might be a false negative, since I not can’t recreate the issue via the WD15 :/ Go figure.

        I checked to see if anything has changed WRT my system configuration. Was (and still is) in airplane mode. No MS updates have been applied, no new application installs, and I haven’t run any Dell driver updates (Dell Command Update is set to manual). Just a shutdown and startup…

        I will keep an eye on it and let you know if anything develops!

        Thanks for keeping tabs on this issue and staying in touch with the community (I know Dell isn’t)!

        • Bob Boerner Bob Boerner Reply

          Glad to hear things are working better, I can certainly appreciate the frustration with regard to the inconsistent behavior 🙂

          While I wouldn’t suggest altering a working configuration, as you mentioned you had Airplane mode enabled as time progresses and logistics allow for it you may want to disable Airplane mode to see if the errant behavior returns (in cases such as this I only recommend changing one variable at a time).

          If it does, try lowering the transmit power of the Wi-Fi adapter as we describe in the latest update at the top of the post to see if that helps. As I am guessing you are using a wired Ethernet connection in the Dell dock using Airplane mode as a workaround obviously doesn’t have much of an impact, but the additional data point may be useful.

  6. supe Reply

    Even though I don’t have a Plugable dock, I wanted to post my experience with my xps 9350 and wd15 dock. Interaction with dell support was superfluous at best, in reading forum posts I decided to focus on the wifi card interaction as that seemed to have an effect on my connectivity issue. I ended up replacing the dell 1820 card with a dell killer 1535, and eureka, my issues with connective are gone. Everything works at full wifi strength on both bands as well as with Bluetooth.

    • Bob Boerner Bob Boerner Reply

      Thanks for providing that new data point. We have read in Dell’s forums where customers have tried a similar tactic by replacing the Dell 1820 card (which I believe is based on a Broadcom chipset) with an Intel chipset adapter. There seem to be conflicting reports in the forums as to the effectiveness of the swap using the Intel adapter, but your experience with the Killer variant is most interesting and hopefully will help others.

      Thanks again for sharing!

  7. Kip Shields Reply

    A data point for your engineers to consider: the 1.2.3 BIOS does not appear to have the USB-C connectivity issues that are present in all newer versions. I’m managing a fleet of over 100 9350s and a few have exhibited some very strange behaviors related to the Broadcom 1820A (cyclical bluescreens only under some user profiles, for example). We’ll be trying out some of the Intel 7265 adapters to see if there’s any improvement, but ultimately the fix needs to come from firmware. Good luck and thanks for posting this!

    • Bob Boerner Bob Boerner Reply

      Thanks for sharing Kip, that is great info especially since you have a large sample size to pull from. Please let us know if switching to the Intel Wi-FI adapter helps as that will be another good data point.

      Thanks again for sharing!

      • Kip Shields Reply

        Bob, so far so good on replacing the 1820A with the 7265 adapter under the 1.4.4 BIOS. We’d never been able to successfully complete system imaging using a USB-C ethernet adapter. I’m planning on replacing all of our 1820A wireless cards with the 7265s based on the low price point and relative ease of installation.

        • Bob Boerner Bob Boerner Reply

          Hi Kip, thanks for getting back. Glad to hear that replacing the Dell card with the Intel unit while using the latest BIOS has helped. Also very interesting the data point in regard to the USB-C Ethernet adapter. Please let us know if the results continue with the same trend once you deploy at scale.

          Thanks once again for sharing!

  8. Darren Carey Reply

    Good article. I’ve been using the Dell tb15 dock for 5 months and have had enough of it exhibiting so many issues so gonna look at your products.

  9. Dave Reply

    Amazing work on helping track this down. I’m using the USB-C to Thunderbolt 3 Dual DisplayPort Adapter with my Dell XPS 15 (9550) and had some pretty annoying scree flicker issues, even with all the latest drivers and BIOS installed. I noticed a definite correlation between this issue and Wifi bandwidth usage, which seemed really odd. Setting the Wifi adapter power to 75% seems to have fixed it! Great product, and excellent support!

    • Bob Boerner Bob Boerner Reply

      Hi Michele,

      Thanks for posting. I took a quick look on the page you link to and the system BIOS, Thunderbolt Driver, Thunderbolt NVM listed have been released for some time now. Dell unfortunately has a habit of changing the ‘Last Updated’ field of a driver entry even if the driver itself has not changed. For example as of today, the Thunderbolt driver listed has been released for some time but the ‘Last Updated’ field is showing September 13. The Intel graphics driver seems to be the sole item actually updated recently, on September 7th.

      That said, our recommendations in the post still apply. Ensure that the BIOS, Thunderbolt driver, Thunderbolt NVM and GPU driver are the latest. If things still aren’t working properly, try lowering the transmit power of the internal Wi-FI adapter as shown in the update to the post.

  10. Jay Luke Reply

    Bob, thanks for your continued support in this thread.

    Question for you or any of your readers: can anyone out there running any variant of Linux on their Dell XPS 15 9550 report that they were able to resolve the screen-flicker issues reported here? I purchased a pluggable Thunderbolt3-to-dual-HDMI adaptor, and it works out of the box, except for the occasional display glitch that leaves one monitor garbled with vertical lines. When that happens I have to unplug the adaptor (or the monitor from the adaptor) and plug it back in. The problem with that is I have to take a minute or two to move my taskbars and open windows back to their prior locations, which just destroys my workflow. At its worst it might happen a couple of times per hour. I provide more details on this reddit thread:

    • Bob Boerner Bob Boerner Reply

      Hi Jay,

      Thanks for posting, and glad the post has helped. To your specific question, very interesting behavior shown in the screenshot of your reddit thread and I believe it differs somewhat from what others have reported (especially since disabling Wi-FI had no effect).

      A quick question for you, are you also able to boot into Windows to allow for updating the BIOS and Thunderbolt NVM firmware? I ask because to my knowledge while it is possible to update the BIOS while running Linux it isn’t possible to update the Thunderbolt NVM firmware. Dell has two threads about this if you are curious -> and

      Assuming that the BIOS and NVM firmware are up to date, as the behavior seems to only affect one display, there are a few quick things to try an isolate the behavior further. The first would be to swap the HDMI cable going to the affected display with a new one to help rule out the cable as the cause. You may have already tried that, but it is a good thing to double-check.

      If swapping the cable doesn’t help, the next step would be to swap the HDMI cable connections first at the monitor end to see if the behavior follows the output port of the adapter or stays with the original monitor. This will let us know if the specific port or the monitor is part of the issue.

      If swapping the HDMI cable doesn’t help, please send an email to and reference this comment and we will determine the next steps from there.

      Thank you,

      Plugable Technologies

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