RE: Dell Inspiron 7567 UHD model problem with 4K Video on Youtube
What kind of bandwidth do you have? Are you using a wireless connection? If so, what speed - and what type of Internet connection do you have (DSL, cable, etc.)-- and what speed?
4K video is a lot more demanding than FHD video -- rough estimate is that you need a spare (unused) 15-20 Mbps just for that one stream. If your cable bandwidth is 30 Mbps (common), make sure no one else in the home is using bandwidth at that time. If you have a DSL connection (Frontier, etc.) you can just about forget 4K streaming - you're lucky to get 6-10 Mbps total.