punktfunk docs

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 uses UDP port 9777 (plus the data port); GameStream/Moonlight uses its standard ports. Allow them on the host's firewall.

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 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.

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.
Confirm PUNKTFUNK_COMPOSITOR in host.env matches your desktop.

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

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.

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

Lower the bitrate. On a busy or Wi-Fi link, the requested bitrate may be too high — the Apple app's 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; cap concurrency with --max-concurrent.

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.