Got a Killer WIFI card inside ???  If yes OPEN Killer Control center > Settings > Disable Advanced stream detect  
So I just got my xps13 9310 three weeks ago, and have been pretty happy about the experience so far. However, I have noticed an issue with video streaming online (youtube). Whenever I tried to stream a video, it automatically set the resolution to 720p. Youtube will even buffer at 1080p resolution sometimes. But my wifi speed is pretty fast (over 100mbps download and upload). I have saimilar issue with Zoom as well. The video quality not good and laggy. I am able to stream video at 4k resolution with the same wifi on my phone and ipad, or even anothor laptop, however.  Also, when I turned on a vpn connection, I am able to stream 4k youtube video on my xps again. I don't know why. Could someone explain this ? Thanks! 
XPS13 9310 Online streaming buffering