I have some 4K movies on my 2017 5k SSD iMac that I would like to stream to my Apple TV 4K through Home Sharing or Plex. I have 100mbit down and 10mbit up. The Apple TV has wired internet, and the iMac has wifi.
I have previously been using this setup for 1080p and it works perfect. But what about 4K? Does the iMac use the 10mbit up to send the data to the Apple TV? Or how does that work? I’m just wondering I need to get higher internet speeds or not.
Does HDR work through Home Sharing btw?
There are no simple answer to your questions. It all depends ....
1. Assuming your 100/10 Mb results are an internet test from something like speed test, as stated by "vertical smile" that is irrelevant for local media on a local network. To determine your local network capabilities you can use an app like Lakehorns' Network Speed Tester. Install on your mac and your Apple TV.
Here are my hardwired results as shown on my Apple TV:
and my wireless results (5 Ghz):
Bandwidth needed depends on the media and the application serving the media to the Apple TV. For Plex I have seen a ripped 4K movie peaking at 267 Mbps. Average is much less, ~42 Mbps, depending upon the content.
Plex Wired:
Plex Wireless:
An iTunes Movies Anywhere 4K import ranged from about 15-25 Mbps. I use Infuse when I want a full DTS-MA soundtrack, but don't have the Infuse bandwidth results.
3. Home Sharing can show different movies that iTunes. It will show download iTunes movies, but not movies imported from Movies Anywhere. Cannot confirm or deny that home sharing does not do HDR.
4. A hardwired connection is going to give you the best results. Wireless can be extremely variable, particularly if you are in an area with congested networks. In Plex I often get the "your server is not fast enough to stream this video" message" even though I have plenty of horsepower left on my Plex server and the network test shows that I have ample bandwidth. Still trying to figure it out.
In summary:
1. Get the fastest network connection available between your iMac and Apple TV. Hardwired is likely best.
2. Experiment with different apps (Plex, Infuse, iTunes Movies, Home Sharing, ...) to see which gives the best results.