Moonlight & Sunshine troubleshooting guides
Short, sourced answers for the problems people hit most when streaming games from a PC to a TV, Steam Deck or Apple TV. Each guide starts with the likely cause, gives checks in a sensible order, and links to the official Moonlight and Sunshine documentation it is based on. Every guide can open the free Couch Lag app with that problem already selected.
All guides checked October 30, 2026 against Moonlight PC v6.2.0 and Sunshine v2026.914.233613 (latest stable releases) and their documentation.
Stream won’t start or shows nothing
- Moonlight can’t find or reach your PC
The PC doesn’t appear or won’t connect: add by IP, firewall ports, VPNs and conflicting apps.
- Sunshine error 503
What each of Sunshine’s three 503 messages means, read from its source code, and what to do.
- Black screen but audio works
The stream connects and plays sound, but the picture stays black. Display, GPU, HDR and capture checks.
- Streaming without a dummy plug
Why headless hosts fail and the options: dummy plug, virtual display, Apollo and Sunshine display settings.
Picture and sound problems
- Moonlight stutters every few seconds
Hitches on a steady rhythm: stats overlay, Wi-Fi scans, Bluetooth, iperf3 and host-side checks.
- Washed-out or dark HDR
Washed-out or dark colours with HDR. Requirements, the Moonlight HDR switch, calibration and Apple TV Match Content.
- No audio in Moonlight
No sound on the client, sound stuck on the PC, or PC audio missing after you stop streaming.
Settings for your device
- Bitrate by resolution and frame rate
Moonlight’s default bitrates for 720p to 4K at 30–120 fps, from its source code, and when to go lower.
- Best Moonlight settings for Apple TV
Every Apple TV Moonlight setting with its default, sensible starting values, HDR and Match Content.
- Steam Deck black screen
Deck as client or as Sunshine host: the 2026 Game Mode issues and what to try.