This is true. The TB15 can support two 4K connections simultaneously or one 5K connection. The only thing is, I'm not quite sure what you're responding to. I'm not sure it has any bearing on the current conversation. But maybe I'm missing something.
I see, you must be responding to businessguy22. He's trying to connect three monitors. Your point may very well apply.
Atin90 posted a possible solution in another thread.
In the device manager find the Dell Wireless card under Network Adapters. Go to advanced properties and scroll down the list until you find "Power Output" adjust the value to 50% and select OK.
I have the XPS 15 - 9550. I don't have the TB15, but I do have the Startech TB32DP2 Thunderbolt 3 to dual display port. I have experienced the same DisplayPort issues as described on the TB15. Typically I might get 5-10 min before the Thunderport crashes. I have a a single 4K Asus PB287Q connected to the Startech.
After adjusting the WiFi output power to 50% as atin90 suggested, the system ran for over 5 hours.
I adjusted back to 100% power to see what would happen. On hitting 'OK' on the network properties card the display IMMEDIATELY dropped out and then came back. Within 2 minutes the TB3 port crashed again. I adjusted back to 50% and plugged the TB32DP2 back in and the system was again operating without any issues.
I have tried this a couple of times with similar results and now have the WiFi Power Output set to 75%. No issues for 40 min.
This is even more disturbing than it being an issue with a peripheral such as the TB15 dock or TB32DP2. This is pointing towards a hardware issue with the XPS15. Insufficient power available on the supply rail? Poor EMI design/shielding? I'm not sure how they're going to fix this one in drivers or BIOS... unless the next version of the wireless card driver remaps the output power settings to lower levels. ie. 75% becomes the new 100% :-(
Has anybody tried replacing the Dell WiFi card with a 3rd party card such as Intel? If it's an EMI issue this would change things up a bit; provided that the Dell card isn't just a re-branded Intel card.
I can confirm that there is also something wrong with the wifi. As suggested by other people on the board, I disabled the wifi and the TB15 works completely fine for me. I also have a USB hub and not plugging anything into the dock except for 3 x external monitors. I can close the LID and no issues at all! Once I turn on the wifi, all *** breaks loose and the monitors disconnect every few minutes.
My setup is 3 x LCD IPS monitors connected directly to the TB15 dock with a 9350 Lap top.
I'm pretty sure that I have tested with Wi-Fi turned off before, without success. But I just lowered the power output to 50% on the Wi-Fi. Let's see what happens. I'll report back the next day or two. Flamesfan, can you point me in the direction of that other thread? Want to know exactly what symptoms were eradicated by this there are a number of symptoms that were bandying about and treating as if they're all the same when they might not be.
Same issue here with XPS13 9350, connecting 4K Samsung though Startech TB32DP2 Thunderbolt 3.
With the WiFi ON, the Startech is recognized and appears in the Attached Thunderbolt Devices menu. The connected Samsung 4K screen lights up fine and runs full res at 60Hz (though DP2 cable). The first time I attached the screen it stayed on for probably 10 minutes before the first signs of trouble came. The attached screen started blacking out and then the Startech completely dropped out.
Now I have the same repetitive scenario - in less than a minute after starting the laptop, the attached screen blacks out, then both screens (built in and attached) start flashing for 10-20 seconds until the Startech drops out completely from the Attached Thunderbolt Devices menu. I have to plug the Startech out and then back in to get the attached screen back online, but the flashing starts almost immediately, and this goes on, rendering the setup completely unusable.
Earlier I was using a "no-brand" UCB-C to HDMI adapter plugged in the same port. The attached 4K screen was appearing (max 30Hz) and occasionally blacking out, sometimes quite often. Annoying but at least usable as opposed to the above T3 setup. I have noticed that using BT mouse/keyboard was affecting the stability of the screen link, probably the WiFi as well.
After reading though the forum I tried running the TB3 setup in "airplane" mode and indeed the screen works fine now. I reduced the WiFi to 75% but occasionally the screen flashes, so I drop the WiFI power setting further down to 50%. Still I get the 4K flash once in a while... Clearly TB3 link to the screen is not entirely stable.
For now I'm fine as I'm using another Startech dongle USB3 to RJ45 connection and running my internet through LAN cable. Once I'm out the office I can use the WiFi as nothing is attached to the TB3 port. But I don't think that should be the solution (not for a 2000$ high end Dell laptop at least). And ultimately I would like to see the external screen stable on at all times.
After dialing the WiFi power back to 50% the Thunderbolt connection to the Startech TB32DP2 dual display port adapter has been solid. However, at 50% wifi power the bluetooth transceiver over powers the wifi connection and the wifi bit error rate renders the wifi connection useless. This happens whether a bluetooth headset is connected or a bluetooth mouse. When transferring a large file and watching the wifi in task manager you can watch the effect on throughput by cycling the bluetooth device on and off. Turning wifi back up to 100% allows simultaneous use of wifi and bluetooth... but almost instantly the thunderbolt port fails.
I've tried all available solutions on my XPS 9350. The only way to get close to the "nirvana" is connecting the 4K screen though TB3, Startech dongle TB3 to DVI 1.2, high performance mode on the laptop and active Airplane mode. And the Wifi card power option is at 50% but that won't matter anyway, since the Wifi is disabled in the Airplane mode.
With the above, the external screen works (almost) stable at 4K 60Hz, but at random intervals, say 10-12 min the external screen blinks which is quite annoying. I noticed that the XPS doesn't like specific web pages for example, which when opened, make the external screen to start blinking every 10-15 sec, rendering all work impossible.
Is there any update from Dell on the issue? What happened with the end of June "final solution"??