Does an Apple TV stream 4K movies if the Internet connection is somewhat less than the recommended 25Mbps? This is to decide whether to buy an AppleTV 4K or not:

For example, some areas may have an 18 to 22Mbps Internet connection, and is just about 10% to 20% lower than the official recommended 25Mbps.

And since the 4K movie cannot be downloaded but can only be streamed, and will be "downgraded" to the next lower resolution (from 4K to 1080p), will a connection of 18 to 22Mbps be able to stream a 4K movie?

Some factors:


If it is not an action movie, it may not require 25Mbps.
If it is 22Mbps, it is about 10% less than the recommended 25Mbps, so if Apple TV can buffer up 10% of the movie: 9 minutes of it out of a 90 minute movie, then mathematically, the whole movie will play till the end smoothly if the user is willing to wait for 9 minutes of start time, or even a 4.5 minute initial wait plus a middle intermission restroom break of another 4.5 minutes, instead of not being able to see it in 4K at all.
Yes, you can stream 4k movies on the Apple TV 4k with a somewhat less than the recommended 25 Mbps internet connection.

In practice the available bandwidth for streaming the movie should not drop 15 Mbps to ensure 4k streaming. So real life experience depends a lot on what else you're using your 22 Mbps internet connection for at the same time.

How exactly the streaming quality is determined depends on the app you're using to view the movie. For example Netflix allows you to lock the quality setting to High, but you might experience lots of waits for rebuffering during the movie, if your internet connection is too slow.

If the movie is streamed from the iTunes Movies and TV Shows app, you can adjust the quality in the general AppleTV settings in the menu Settings > Apps > iTunes Movies and TV Shows.

From this menu you can disable "QuickStart". This means that you'll have a wait before the movie starts playing, but it will display in the best available quality even on a slow internet connection.