RE: Trouble with XPS 15 9550, USB-C/Thunderbolt 3, and external monitors
Looks like the last two driver updates, the firmware one for usb (TB15 has to be plugged in), and the intel video drivers solved it but I have only been testing for a few hours. I have wifi on and connected plus Ethernet in the dock. Haven't seen any hick ups and the dock doesn't seem that warm. Watched a bunch of 4k footage on youtube with my secondary monitor in the dock. Still going strong.
Besides the screen going to sleep, I had one other issue prior to this update. If I left my laptop the screen would timeout and go black, as it should. But I could never wake the secondary screen. I would have to unplug and power down the monitor. Replug in the dock and turn on the monitor. Minor issue, I hope that was solved too.
So far it's working. We will see how it is in a few days.