Is there an existing issue for this?
Is your issue described in the documentation?
Is your issue present in the latest beta/pre-release?
This issue is present in the latest pre-release
Describe the Bug
Sunshine hardcodes DSCP tags on Linux (src/platform/linux/misc.cpp, enable_socket_qos()): audio CS6 (48), video CS5 (40), with no config option.
CS6 maps to the WMM AC_VO (voice) WiFi queue, which is unreliable for sustained downlink on some consumer AP/client combinations. On a TP-Link Archer AX10 to a Steam Deck OLED, the audio stream suffered episodic bursty loss (30-60 unrecoverable audio FEC events/min, heard as intermittent severe crackle) while the channel was measured clean (~6% airtime, no neighbor APs, -110 dBm noise, zero client TX retries) and untagged synthetic UDP replicating the exact stream shape had zero loss running concurrently. Video (CS5) was unaffected. The pathology engages per WiFi association, so it appears intermittent and unreproducible.
Stripping DSCP at host egress fixes it instantly (audio drop rate to 0, verified by tone capture on the client):
iptables -t mangle -A POSTROUTING -o <iface> -p udp --sport 47998:48000 -j DSCP --set-dscp 0
Request: a config option to disable DSCP tagging or set the per-type values (e.g. qos = disabled or audio_dscp = 0..63). Happy to submit a PR. A note in the audio troubleshooting docs would also likely resolve a class of "audio stutters on WiFi but the network is fine" reports.
Related client-side investigation with full measurements: moonlight-stream/moonlight-qt#1978
Expected Behavior
A supported way to disable or adjust DSCP tagging, without host firewall mangle rules.
Additional Context
Fix verified over multiple 90 s tone-capture windows and hours of gameplay. The loss is invariant to bitrate (2-20 Mbps), fps (30-90), resolution, and codec, ruling out congestion.
Host Operating System
Linux
Operating System Version
Ubuntu 24.04
Architecture
amd64/x86_64
Package
Linux - deb
GPU Type
NVIDIA
GPU Model
GeForce RTX 2080 Super
GPU Driver/Mesa Version
580.173.02 (proprietary), X11
Capture Method
NvFBC (Linux)
Apps
Log output
Online logs
No response
Is there an existing issue for this?
Is your issue described in the documentation?
Is your issue present in the latest beta/pre-release?
This issue is present in the latest pre-release
Describe the Bug
Sunshine hardcodes DSCP tags on Linux (
src/platform/linux/misc.cpp,enable_socket_qos()): audio CS6 (48), video CS5 (40), with no config option.CS6 maps to the WMM AC_VO (voice) WiFi queue, which is unreliable for sustained downlink on some consumer AP/client combinations. On a TP-Link Archer AX10 to a Steam Deck OLED, the audio stream suffered episodic bursty loss (30-60 unrecoverable audio FEC events/min, heard as intermittent severe crackle) while the channel was measured clean (~6% airtime, no neighbor APs, -110 dBm noise, zero client TX retries) and untagged synthetic UDP replicating the exact stream shape had zero loss running concurrently. Video (CS5) was unaffected. The pathology engages per WiFi association, so it appears intermittent and unreproducible.
Stripping DSCP at host egress fixes it instantly (audio drop rate to 0, verified by tone capture on the client):
Request: a config option to disable DSCP tagging or set the per-type values (e.g.
qos = disabledoraudio_dscp = 0..63). Happy to submit a PR. A note in the audio troubleshooting docs would also likely resolve a class of "audio stutters on WiFi but the network is fine" reports.Related client-side investigation with full measurements: moonlight-stream/moonlight-qt#1978
Expected Behavior
A supported way to disable or adjust DSCP tagging, without host firewall mangle rules.
Additional Context
Fix verified over multiple 90 s tone-capture windows and hours of gameplay. The loss is invariant to bitrate (2-20 Mbps), fps (30-90), resolution, and codec, ruling out congestion.
Host Operating System
Linux
Operating System Version
Ubuntu 24.04
Architecture
amd64/x86_64
Package
Linux - deb
GPU Type
NVIDIA
GPU Model
GeForce RTX 2080 Super
GPU Driver/Mesa Version
580.173.02 (proprietary), X11
Capture Method
NvFBC (Linux)
Apps
Log output
Online logs
No response