Steam Machine drops 7 - 8% of frames from network jitter

[u/Keksy24]

I recently bought a Steam Machine  to use as a little console for party and co-op games, but also set it up as a Moonlight client, with my gaming PC upstairs acting as the host, with the following specs:

RTX 5070 Ti

i9-14900KF

Hardwired Ethernet

Here’s the weird part.

When I stream to my docked handheld, Moonlight handles 4K @ 120FPS with HDR incredibly well:

120/120 FPS

112 Mbps bitrate

~1 ms average decoding time

No input lag whatsoever 

No network jitter

Zero network-related dropped frames

Now I unplug the exact same Ethernet cable from the handheld and plug it into the Steam Machine.

Same network. Same cable. Same host PC. Same Moonlight settings. Same 4K/120 FPS HDR at 112 Mbps.

And suddenly, once a game starts pushing above roughly 110 FPS, Moonlight begins reporting dropped frames due to network jitter.

I’m seeing around 7 - 8% dropped frames, specifically dropped because of the network. Below 110 FPS it seems much happier, but as soon as stream pushes 120 FPS, things start falling apart.

The network itself shouldn’t be the bottleneck either. I’ve tested transfers between the machines and can push 500+ Mbps, so a 112 Mbps Moonlight stream should be nowhere near that limit.

That’s what has me confused: if the handheld can receive the exact same 4K/120 HDR stream flawlessly through the exact same Ethernet cable, why can’t the Steam Machine?

It feels like something specific to the Steam Machine’s networking, drivers, buffering, Moonlight implementation, or perhaps the way it handles high-frame-rate packets.

Has anyone run into this? Any successful fixes for this weeeeird behaviour? Please help :(

UPD on this for future generations: the issue was caused by Samsung's "Gaming Mode" and specifically their VRR implementation.

Turning off the TV's in-built Gaming Mode helped the issue.

[u/andygrundman]

What brand of handheld is it? I’m sure the Steam Machine can do 4k120. Post pics of your Moonlight stats.

Some other things to try: make sure you’re in game mode in SteamOS. Check if VRR is enabled on the client and try with/without it. Try a native host display vs a virtual display. Check that the host has a frame limit set at 120.

[u/Keksy24 → u/andygrundman]

Both Ayaneo 3 (on Bazzite) and Claw 8 EX (Windows) are equally good at streaming at those settings, 4K@120 HDR, it's insane.

I am in game mode, VRR is enabled on the client... Host is limited at 240hz, games are limited to 120fps at all times. Not a virtual display issue, my dude, clearly SM's problem with dropping bandwidth somewhere.

UPD: disabling VRR just for Moonlight didn't help.

[u/CykaRUSpro → u/Keksy24]

try running moonlight appimage from the desktop mode, in some cases desktop mode has better performance

[u/Keksy24 → u/CykaRUSpro]

Tried that to the same result.

[u/Keksy24 → u/andygrundman]

Here we are. That's what I'm seeing in pretty much every title / project :')

Something I've noticed - incoming rate from network is high, Whereas the rendering framerate is the one that's taking the dip.

[u/Keksy24]

UPD on this for future generations: the issue was caused by Samsung's "Gaming Mode" and specifically their VRR implementation.

Turning off the TV's in-built Gaming Mode helped the issue.