@Trinh Nguyen Unfortunately, this is a known issue documented in this KB article. As you'll read, Dell acknowledged the issue and then basically said they weren't going to fix it because they consider the XPS 13 9350 end-of-life. They didn't even give a technical explanation of underlying cause, never mind committing to providing a fix -- although it's possible that the underlying cause is a hardware issue that can't be fixed with an update. We may never know. The only workaround they suggest is to buy a dock, which seems a bit ridiculous given that the whole point of using a USB-C display is to avoid having to use a dock in the first place.
The closest you can get to maintaining single cable connectivity would be to use an adapter like this one that will allow you to continue running video and power through a single connector. Connect a DisplayPort cable to the P2720DC's DP input and run the USB-C cable from the P2720DC to the adapter to provide power. But then you lose the ability to use the USB ports built into the display, since it seems the only "upstream" USB port that Dell is providing on their new displays is the USB-C port, and the adapter I linked doesn't support data passthrough. Dell's displays used to have a regular USB 3.0 port for "upstream" connectivity.
I realize that's far from an ideal solution, but unfortunately that's the deal on the XPS 13 9350. Since that KB article was written, it came out that this issue also affects the XPS 15 9550 and its sister system the Precision 5510, but Dell never even updated that article to reflect that. So I've been doing what I can to field questions from people using those systems experiencing the exact same issue that you are.
I wish I had better news for you on this.
@Trinh Nguyen I absolutely understand your frustration, and this is one of those cases where I'm disappointed with Dell myself for not delivering a fix. And sadly there are other interoperability issues I know of where Dell hasn't even bothered to write a KB article despite reports on this forum from multiple users experiencing a problem. For example, Inspiron xx93 systems are limited to 1080p on their HDMI outputs even though their specs claim HDMI 1.4b, which should support QHD or 4K 30 Hz, and the XPS 15 9570 can't use HDMI to DVI adapters/cables even though it should be able to. But you won't find any official documentation from Dell about those issues at all.
But back to your issue, unfortunately Dell sales reps simply won't know about issues like this. They're expected to be familiar with a broad range of products, which means they simply won't always know about any particular product in great depth. This case is an interoperability issue that only affects one system that's documented (plus two that aren't), and the issue shouldn't even exist at all, so it's just not something that would come up in training for a sales rep. The only way they'd likely know about this issue was if they just happened to hear complaints about it before. But I realize that doesn't change the bad experience that you had.
So on that note, I wanted to clarify that this issue only affects the specific combination of a) using an XPS 13 9350 (or one of the other two systems I mentioned), and b) using a USB-C to USB-C cable, and c) connecting to the USB-C input of a Dell USB-C display. If you change any one of those variables, the issue goes away. I know you said you don't want to change displays, but if you're willing to reconsider that, other XPS 13 9350 users have found that they can use other USB-C displays just fine with their system, so that might be an option worth considering. But if you're certain you want to keep both your laptop and the display, the adapter I mentioned would work if you were willing to give up USB data. The only other option that would maintain full functionality but completely wipe out the single cable convenience of USB-C would be to do this:
- Use a USB-C to DisplayPort cable to connect the XPS 13 to the display for video.
- Use a USB-C to USB-A cable to connect the display's USB-C port to the XPS 13's USB-A port for USB data.
- Keep the XPS 13's power adapter directly connected for power.
Again, I realize there's no good option here. I just wanted to suggest what I could under the circumstances.
@Trinh Nguyen No, I meant exactly what I wrote above. You'd end up with 3 cables connected to your system. You'd have a USB-C to DisplayPort cable for video (you can use a USB-C to HDMI cable if you prefer, but I tend to prefer USB-C to DP since USB-C ports use DisplayPort anyway), plus a USB-C to USB-A cable for USB data, and then the power adapter.
@Trinh Nguyen whoever you're talking to doesn't know what they're talking about. The display has a native USB-C input, so you shouldn't "need to have an adapter" in the first place. But it's true that if you use a USB-C to DP or USB-C to HDMI cable, you'll be able to get video out of your system to the display. But that type of cable will ONLY carry video. It won't carry USB data or allow your laptop to charge from the display. The adapter I suggested in my first post would at least give you video and power through a single connection to your system (with two cables running from that adapter to the display), but won't give you USB data at all, because now you'll be using the display's USB-C port purely for power. There might be an adapter that would plug into your USB-C port and give you a video output, a power input, and a USB 3.x data connector, in which case you'd have 3 cables running from the display to the adapter but only a single cable from the adapter to plug into your system, but I don't know of one offhand. It's also a bit past midnight where I am, so I'm going to bed, but I'll see if I can find an adapter like that for you in the morning. You might end up finding that the adapter costs less than shipping the display back. Are you sure that Dell won't pay for return shipping even within the return period?
