apple tv stutter playback from iMac over ethernet or WiFi

Yes. I reset everything, including the TV.

I also considered that the TV might be doing some jitter reduction or other things that might affect playback. I changed all that so it's turned off.

Again, the only thing that changed is the update to 13.3.

I reset the router per your suggestion, even though I disagree it needs to be reset (EVER).

It's a quality router that has had that long uptime without issues until this 13.3 update.

I've not had any internet outages or slow speeds or memory leaks like consumer grade routers.

BUT... Something isn't working and anything is worth trying.

https://dl.ubnt.com/datasheets/edgemax/EdgeRouter_X_DS.pdf

The router is plugged directly into my FiOS handoff (fiber optic).

The house is 2200 Sq Ft.

I probably have 25+ devices on the network.

As a tip, I made my netmask 255.255.0.0. I edit the dhcp.conf on the router so it assigns static IPs. I get the MAC address of the devices via the settings type screens (it's available on the ATV, iPhone, computers, etc.). Because the netmask is 255.255.0.0, I can use 192.168.0.* for routers and switches (the switches are smart switches), 192.168.1.* for computers, 192.168.2.* for mobile devices, 192.168.3.* for home entertainment devices (ATV, the Denon receiver, the smart TV, Roku, XBox) and so on. It's a nice and handy configuration.

The Apple TV is connected to the network via gigabit ETHERNET. I get 200/200 (mbps up/down) at the switch where the Apple TV is plugged in. I tried WiFi to see if that would fix it. It doesn't, but it seems to lessen the stutter effect.

The Ubiquiti router and WiFi setup is a mesh and roaming one. Devices automatically connect to the nearest access point (I have 2) and assign channels to avoid too many on one channel, and chooses 5GHz vs 2.4GHz automatically, too.

I get 200/200 speedtest.net (and speedtest command from terminal) over WiFi.

My network is so stable my router was up 245+ days with zero issues. Until the 13.3 update to the ATV and the reboot I did today to see if that will fix it.

I agree that if you have a crappy modem/router, like the ones some of the ISPs give you, that you should reboot often and especially as first thing to try to fix something not working. Those routers are terrible and have memory leaks. The Spectrum internet I had would stop working when the memory leaks caused the router software to run out of memory. The ubiquiti router runs linux and has no memory leaks.

My HOA forces me to pay for Spectrum, so I have two internet connections to my home. I have the Spectrum router connected to the Ubiquiti one. The Rokus can play Spectrum TV (every channel we get) using the Spectrum app, but it only works if the connection goes through the Spectrum router. That is, it doesn't work using the FiOS connection. Since I have the 255.255.0.0 setup, I made a 192.168.100.* subnet that uses Spectrum router as the default gateway. The rokus are assigned static IPs in that subnet. I can watch Spectrum TV via the app. I can also connect to the Spectrum router via its WiFi and get a DHCP dynamic IP from the 192.168.100.* range - this makes it so I can use Spectrum at will, and especially when the FiOS isn't working.

That said, I've had FiOS for 4+ years and have never seen it down.

I have NO problem with content streamed from anywhere, 4K or even 8K 60FPS demos on YouTube. It's only streaming from playlists on my computer to the ATV that there is stuttering. It also seems like the stuttering is worse on my more recent purchases/downloads.

You can buy access points and place them anywhere. They can be powered via PoE (Power over Ethernet) which the Ubuiqiti routers and switches support, or you can power them with a wall plug. If you connect them to Ethernet (PoE), it uses the wire to back haul data to the router. If you don't, they use radio.

I have two access points (A/Ps), one next to the router and one in the middle of the house. Both PoE / Ethernet.

I highly recommend this hardware, but you probably should know your way around the command line, especially as root. Understanding of routing fundamentals would help. The online documentation and forums for Ubiquiti are outstanding.

I like that I can continuously upgrade the network by adding more access points (APs) and ethernet switches.

They have a web interface that shows you a lot of information about your network, including which machines are using bandwidth and even "iMac is using 2G of bandwidth for Netflix" level detail.

I think I paid $50 for the router, which is about the size of a pack of cigarettes. The switches and A/Ps were about $100 each.

Did not fix it, any other ideas?

Like I said, the network wasn't changed at all, just the 13.3 update to the ATVs.

I do not think it has anything to do with the network.

What I have been seeing since this occurred and I am now paying more attention to it is that the TV show seems to buffer way ahead of where it's playing. The progress meter at the bottom where it shows playing point and when you fast forward/rewind starts out transparent and then fills up with a white/grey background as it buffers.

What I do notice is that the stuttering seems to be related to the compression. When the entire screen changes from frame to frame, as when they pan the camera or there's something busy in the background, the stuttering is worst.

I removed download for one of the shows and am re-downloading it to see if that helps.

Changing the video settings on the ATV from 4K to 1080p fixed the stuttering.

it is not the hdmi cables - I got high quality ones to support Atmos and 4k HDR.

It is not the network. I can see the entire show is buffered on the ATV and it still stutters.

I bet it’s a bug in the upscaling software and it doesn’t work well with the content that’s downloaded. Perhaps Apple downloads a higher quality (bitrate) file and streams a lower quality one.

like I said, this bug seems to have been introduced in 13.3.

I have a friend who works for Apple. He says his AirPlay from iPad to his ATV stutters, too.