HD Stream using AirPlay doesn't work

Hi. I assume you're using basic AirPlay (not mirroring) to stream content from an internet server. Does the new ATV 4 have exactly the same internet connection as ATV 3? In particular, does it use the same DNS, VPN, unblocker, etc.?

Intermittent problems are often a result of interference. Interference can be caused by other networks in the neighbourhood or from household electrical items.

You can download and install iStumbler (NetStumbler for windows users) to help you see which channels are used by neighbouring networks so that you can avoid them, but iStumbler will not see household items.

Refer to your router manual for instructions on changing your wifi channel or adjusting your multicast rate.

There are other types of problems that can affect networks, but this is by far the most common, hence worth mentioning first. Networks that have inherent issues can be seen to work differently with different versions of the same software. You might also try moving the Apple TV away from other electrical equipment.

The following article(s) may help you.

Troubleshooting Wi-Fi networks and connections

Recommended Wi-Fi settings

Sources of Interference

Wifi Diagnostic Software (for Mac users)

You may also find some help on this page, where I’ve collected some of the more unusual solutions to network issues.

And your iPad is also connected by ethernet.

You can't assume that, however I have to agree it's probably not your issue.

Try the following steps, check whether things are working after each step where appropriate, before trying the next.

1. Check AirPlay is turned on on the Apple TV (turn it off and on if it already is)
2. Restart the Apple TV (Settings > General > Restart).
3. Restart the Apple TV by removing ALL the cables for 30 seconds.
4. Restart your router. (Also try removing it’s power cord for at least 30 seconds)
5. Restart your mobile device or computer.

You've got data coming via wifi from the router to your iPad (from the internet), you've also got data coming via wifi from the iPad to your router and you have data travelling between the router and the Apple TV over ethernet. So yes it matters about your internet connection because without it there is no data at all.

Hi. When you AirPlay (not mirroring) video from the internet, the URL is sent to ATV which then streams the video direct from the server. So it is essentially the same as using an app on ATV. So your problem with HD on some channels is related to the server and the ATV connection to the internet. That's why I asked whether your ATV 3 and ATV 4 were accessing the internet in the same way, same nameserver, etc. The fact that the audio continues is a little mysterious since it implies the stream is coming through fine. We now have tvOS 10, and the AirPlay implementation has been updated, so that may affect your results.

That to me indicates a strong possibility it is your own network environment, only the environment can change itself without you changing anything.