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
On SteamOS, Sunshine’s Avahi mDNS advertisement fails because Steam’s steamwebhelper appears to also bind to the mDNS port 5353 when Steam is running in the default Gamescope session. Even after disabling systemd-resolved mDNS, Avahi still logs:
Failed to add service 'steamdeck' of type '_nvstream._tcp', ignoring service group ... : Not permitted
and ss -ulpn | grep ':5353' shows steamwebhelper attached to 224.0.0.251:5353. This makes Avahi think another mDNS stack is active, so the Sunshine service is ignored. As a result, Sunshine auto-discovery via mDNS cannot work reliably on SteamOS while Steam is open.
What I confirmed:
avahi-daemon loads the Sunshine service file correctly.
systemd-resolved has MulticastDNS=no.
The remaining mDNS conflict comes from steamwebhelper.
If Steam is not running, Avahi can start normally, but with Steam open the conflict returns.
Possible fixes:
Let Sunshine advertise via a different mechanism than Avahi on SteamOS.
Add a Sunshine option to disable mDNS auto-discovery entirely and rely on manual IP pairing.
Investigate whether Sunshine can register under a different service discovery method that does not conflict with Steam’s mDNS behavior on SteamOS.
Expected Behavior
No response
Additional Context
No response
Host Operating System
Linux
Operating System Version
SteamOS
Architecture
amd64/x86_64
Package
Linux - flathub/flatpak
GPU Type
AMD
GPU Model
Ryzen Z1 Extreme
GPU Driver/Mesa Version
Mesa 25.3.0
Capture Method
None
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
On SteamOS, Sunshine’s Avahi mDNS advertisement fails because Steam’s steamwebhelper appears to also bind to the mDNS port 5353 when Steam is running in the default Gamescope session. Even after disabling systemd-resolved mDNS, Avahi still logs:
Failed to add service 'steamdeck' of type '_nvstream._tcp', ignoring service group ... : Not permitted
and ss -ulpn | grep ':5353' shows steamwebhelper attached to 224.0.0.251:5353. This makes Avahi think another mDNS stack is active, so the Sunshine service is ignored. As a result, Sunshine auto-discovery via mDNS cannot work reliably on SteamOS while Steam is open.
What I confirmed:
avahi-daemon loads the Sunshine service file correctly.
systemd-resolved has MulticastDNS=no.
The remaining mDNS conflict comes from steamwebhelper.
If Steam is not running, Avahi can start normally, but with Steam open the conflict returns.
Possible fixes:
Let Sunshine advertise via a different mechanism than Avahi on SteamOS.
Add a Sunshine option to disable mDNS auto-discovery entirely and rely on manual IP pairing.
Investigate whether Sunshine can register under a different service discovery method that does not conflict with Steam’s mDNS behavior on SteamOS.
Expected Behavior
No response
Additional Context
No response
Host Operating System
Linux
Operating System Version
SteamOS
Architecture
amd64/x86_64
Package
Linux - flathub/flatpak
GPU Type
AMD
GPU Model
Ryzen Z1 Extreme
GPU Driver/Mesa Version
Mesa 25.3.0
Capture Method
None
Apps
Log output
Online logs
No response