punktfunk/docs-site/content/docs/troubleshooting.md

title, description

title	description
Troubleshooting	Common problems setting up or using a punktfunk host, and how to fix them.

Another streaming host (Sunshine, Apollo, …) is installed

Punktfunk is a Moonlight-compatible host. So are Sunshine and its forks (Apollo, Vibeshine, Vibepollo, LuminalShine, …). Running one of them at the same time as Punktfunk is not supported: they bind the same GameStream ports (47984/47989 and 47998–48010, plus a web UI on 47990 that collides with Punktfunk's management API), advertise the same _nvstream mDNS name, and often install a conflicting virtual-display driver. The result is address already in use errors, pairing that silently fails, the wrong host answering a client, and capture/display glitches.

• Punktfunk warns about this automatically: the host logs it at startup (visible in the web console's Logs tab and the system tray tooltip), and the Windows installer warns before installing. To check on demand, run:

  punktfunk-host detect-conflicts
  

  It lists any conflicting host found (installed or running) and exits non-zero if there is one.

• Fix: stop and uninstall the other host, then start Punktfunk — e.g. stop the service (sudo systemctl disable --now sunshine / on Windows sc stop SunshineService) and uninstall it. If you only want to try Punktfunk without removing the other host, at least make sure the other host is fully stopped first (they cannot both run at once).

The host isn't found on the network

• Make sure the host is actually running (systemctl --user status punktfunk-host, or you see it listening in the terminal).
• Host and client must be on the same network/subnet. Discovery uses mDNS, which doesn't cross routed subnets or most VPNs-without-multicast. As a fallback, add the host by IP address in your client.
• A firewall on the host can block it. The native protocol's control plane is a fixed UDP port, 9777 — open this one. The per-session data plane rides a separate, random UDP port and usually needs no firewall rule (see Video is slow to start, or fails across subnets for why, and the one case where opening it helps). GameStream/Moonlight (only with --gamestream) uses TCP 47984/47989/48010 + UDP 47998–48010 (video/FEC 47998, ENet control 47999, audio 48000) + mDNS UDP 5353. Allow those on the host's firewall.

Video is slow to start, or fails across subnets

The native data plane (the raw UDP that carries video, separate from the 9777 control plane) uses a random, per-session UDP port — the host binds 0.0.0.0:0, then tells the client which port it got during the connect handshake. There is no fixed data port.

Video flows host → client, but the client sends the first packet: a small hole-punch datagram to that port. This is deliberate. It lets the host learn the client's real (possibly NAT-translated) source address and stream back to it, so a session can cross a NAT or a stateful inter-VLAN firewall without a forwarded data port. What it means for a host firewall:

• Same LAN, no host firewall (or the port allowed): the punch arrives immediately and video starts at once. Nothing to configure.
• Same LAN, host firewall that denies inbound (ufw/nftables/firewalld default): the punch is dropped, so the host waits ~2.5 s, then falls back to the address the client reported and streams anyway — a stateful firewall admits the return traffic because the host sent first. Net effect: it works, but each session takes ~2.5 s longer to start. That slow start is the symptom of a data-plane rule you're missing.
• Across subnets / NAT: the same punch-then-fallback applies, as long as the host's outbound video can reach the client (the path's stateful firewall then admits the return). If the host itself is behind NAT reached only via a forwarded control port, the data path may not establish — this is the case a fixed, forwardable data port would solve.

To remove the ~2.5 s fallback delay, pin the data port with --data-port (or the PUNKTFUNK_DATA_PORT env in host.env) and open exactly that one port. The host then binds that fixed port, skips the punch-wait, and streams straight to the client — no timeout to pay:

punktfunk-host serve --data-port 9778     # or PUNKTFUNK_DATA_PORT=9778 in host.env
sudo ufw allow 9778/udp                    # open exactly that one port

Two caveats. A fixed data port serves one session at a time; a second concurrent session finds it busy and transparently falls back to a random port + hole-punch (logged). And --data-port streams to the client's reported address, so use it only where that address is reachable — a flat LAN, or a port-forward that doesn't remap the client's source. Leave it off (the default) to keep the NAT-crossing hole-punch. On a normal single-LAN setup you can also just leave the data port closed and accept the one-time ~2.5 s punch-timeout, or not run a host firewall on a trusted LAN at all.

nvidia-smi says it can't communicate with the driver

• The NVIDIA kernel module didn't load. With Secure Boot enabled, enrol the module's signing key: sudo mokutil --import /var/lib/shim-signed/mok/MOK.der, reboot, Enrol MOK at the blue screen (or disable Secure Boot). On Fedora, follow RPM Fusion's Secure Boot steps.
• After a kernel update the module may need a rebuild — reinstall the driver package.

The desktop won't start, or "GPU … not supported by EGL"

The NVIDIA GL/EGL userspace is missing — the base driver package doesn't always include it.

• Ubuntu: sudo apt install libnvidia-gl-<version> (matching your driver).
• Confirm /usr/share/glvnd/egl_vendor.d/10_nvidia.json exists and nvidia-drm modeset is Y.

See GNOME for the GL/EGL userspace details.

Black screen / no picture, but the client connects

• You must be on a Wayland session, not X11 (check the login-screen session picker).
• KWin must be ≥ 6.5.6 (kwin_wayland --version); GNOME ≥ 48; gamescope ≥ 3.16.22. See KDE for the KWin/Wayland requirement and gamescope for the gamescope one.
• If host.env sets PUNKTFUNK_COMPOSITOR, remove it — the host auto-detects the live compositor, and the pin points it at one backend even when a different session is live (it also disables Gaming ↔ Desktop following).

The screen stays black after switching to Game Mode (Nobara)

On distros whose Game Mode is display-manager autologin under plasmalogin (Nobara), a managed takeover from a host 0.19.1 or older could kill the display manager: it trips systemd's start limit and the box stays black until someone restarts it. Recover from a VT (Ctrl+Alt+F3) or SSH:

systemctl --user unmask --runtime 'gamescope-session-plus@*.service'
sudo systemctl reset-failed plasmalogin && sudo systemctl restart plasmalogin

Current hosts detect the display-manager flavor and never mask the session unit there — see gamescope → autologin display managers for the polkit rule that enables the full managed takeover on these boxes (without it the host mirrors Game Mode instead).

Session fails right after editing host.env

• Keys are case-sensitive: punktfunk_gamescope_attach=1 sets nothing — use the exact uppercase names.
• Hardcoded session anchors with the wrong uid (XDG_RUNTIME_DIR=/run/user/1000 when id -u isn't 1000) point the host at another user's PipeWire/D-Bus: audio errors like pw audio connect … Creation failed, no capture, and clients reporting the host as unreachable or asleep. Delete both anchor lines — a systemctl --user service doesn't need them — or fix the uid.
• PUNKTFUNK_COMPOSITOR pins the backend and disables Gaming ↔ Desktop following — remove it on any box that switches sessions.
• The env file is read at service start: systemctl --user restart punktfunk-host after edits.

Capture fails: "Session creation inhibited" (GNOME)

A locked GNOME session blocks screen capture. On an always-on/headless host, disable the lock:

gsettings set org.gnome.desktop.screensaver lock-enabled false
gsettings set org.gnome.desktop.session idle-delay 0

See GNOME → Headless session and Running as a Service.

A controller is detected but does nothing (Bazzite)

The host user needs to be in the input group. On Bazzite:

ujust add-user-to-input-group

Then log out and back in. On other distros this is sudo usermod -aG input $USER + re-login. See Bazzite.

Pairing is rejected / the client can't connect

• The host requires pairing by default. Arm pairing from the web console, then enter the PIN on the client. See Pairing & Trust.
• If you re-installed the host, its identity changed — re-pair the client.

Stutter, drops, or high latency

• Lower the bitrate. On a busy or Wi-Fi link, the requested bitrate may be too high — the native clients' speed test picks a safe value; with Moonlight, set it manually.
• Prefer a wired connection or 5 GHz Wi-Fi between host and client.
• Streaming to many devices at once shares the GPU encoder. The host serves several concurrent native sessions (up to 4 by default); heavy load is usually bitrate-bound, so lower the bitrate first.

Windows: "punktfunk Virtual Display" shows Code 10 in Device Manager

Sessions end with "pf-vdisplay driver interface not found" and Device Manager shows the punktfunk Virtual Display device failed with Code 10 (STATUS_DEVICE_POWER_FAILURE).

This means your Windows version is too old. The virtual-display driver requires the IddCx 1.10 driver framework, which first shipped in Windows 11 22H2 (build 22621) — on Windows 10 (including LTSC) and Windows 11 21H2 the driver installs but cannot start. Reinstalling won't help; the fix is updating to Windows 11 22H2 or newer. (Current installers refuse to run on older Windows for this reason; if you see this, the host was likely installed with an older installer.)

Still stuck?

Run the host with RUST_LOG=info (or debug) and check journalctl --user -u punktfunk-host for the error around the failed connect or capture.