When a row won't start, a source won't appear, a permission is missing, or your Orbit viewers can't watch, the fix is almost always one specific control. This page maps the symptom to the setting that resolves it.
Gut-check first: if a stream "works on another machine but not this one," suspect a VPN or kill-switch (e.g. NordVPN) or macOS Local Network privacy before anything else. These silently block both local NDI discovery and SRT. See Rule out a VPN / kill-switch.
Opening the Dependencies window
This window shows whether the NDI Runtime and GStreamer (needed for SRT) are installed, and on Windows it adds a firewall section.
Click the version string in the header to open About.
Click "System Dependencies & Firewall".
On Windows, this window also auto-opens a second or so after launch if a dependency or firewall issue is detected.
"No Sources" on launch
This is the normal empty state, not an error.
Click "Set up a source" on the No Sources card (or the footer + once rows exist).
Pick a source type in the Select Source Type modal.
Tip: pick GEN (test card) to verify an output path end-to-end with no camera or network source. See Screen / Camera / Test Card sources.
START did nothing / a row was skipped
Pulsar starts what it can and skips anything that isn't fully configured, so the rest of the batch still goes.
Watch for the toast: "Skipped N unstartable outputs (missing URL/source/camera): …" — easy to miss.
SRT caller output: open the output settings and enter a valid
srt://host:portURL. See Outputs (SRT / NDI).SRT source row: open the SRT input modal and configure a Caller URL or a Listener port. See SRT input source.
UE row: select a camera session via the +CAM flow before starting. See Unreal Engine source.
If a Start button isn't showing, nothing is yet both enabled and validly configured — finish setting up a row and it returns.
NDI source not appearing
See also NDI source.
Open the NDI source modal (click the blue NDI pill on the row).
Click "🔄 Refresh Sources" (the list also auto-refreshes every 10 seconds while open).
Still missing? Switch Selection Mode to Auto and enter a broad Search Term with Match Mode = Contains.
Open the Dependencies window and confirm NDI Runtime shows Installed (green).
On Windows, in that window run "Check Firewall Rules" / "✓ Fix Automatically" so
NdiDiscovery.exeis Allowed.On macOS, if other machines can't see this source, check that NDI Firewall Protection (Settings) is off — see the note below.
Rule out a VPN / kill-switch or macOS Local Network privacy — a known cause of NDI sources never appearing.
NDI Firewall Protection blocks external NDI on purpose. When this macOS feature is on, other machines on the LAN can't reach this machine's NDI sources (localhost still works). That's the feature, not a fault — and it's a separate cause from the VPN issue.
GUI screen capture not working
See also Screen / Camera / Test Card sources.
On macOS, grant System Settings → Privacy & Security → Screen Recording and enable Pulsar.
Reopen the GUI source modal and re-select the display under "Monitor to share".
Click "🔄 Refresh Monitors" if the right display isn't listed.
To test without a real screen, add a separate GEN row.
Camera overlay not appearing
In the GUI source modal, pick a camera under "Camera Overlay" (default is No camera).
On macOS, approve the camera prompt. If you deny it, the selection resets to No camera.
Still missing? Grant System Settings → Privacy & Security → Camera, then re-select the camera.
FILE row shows "No File"
Turn on FILE sources in Settings → Beta Features first. See also File source.
Open the FILE source modal and click "📁 Choose File".
Confirm the file is still where it was (not moved or deleted).
On macOS, if Start fails with a Full Disk Access toast, grant it in System Settings, then restart that stream — it won't resume on its own.
SRT listener not receiving
See also SRT input source.
Open the SRT modal and confirm the mode is Listener (not Caller).
Verify the local IP, Port (listener default 21010), and Passphrase match what the sender uses.
Use the Copy button beside "Sender URL (for caller)" and hand that exact string to the upstream sender.
Clear any port-conflict warning — Pulsar auto-adjusts most conflicts and shows an amber duplicate-URL badge when it can't.
On Windows, run Fix Automatically in the Dependencies window so
gst-launchis Allowed.Rule out a VPN / kill-switch blocking local/outbound SRT.
Orbit clients cannot connect
Turn on Orbit in Settings → Orbit Streaming first. See also Orbit streaming.
Confirm the per-row ORBIT button is on for the rows you want shared.
In Orbit Device Control, check the access code isn't revoked or expired.
If "Require Approval for Join Requests" is on, approve the device under Pending Approval Requests.
For devices elsewhere on the LAN (not just localhost), turn on "Allow Remote Access" — and restart the app if prompted.
Excess Orbit disconnects
Usually aggressive timeouts.
In Orbit Device Control, open Timeout & Auto-Disconnect.
Relax Inactivity (default 30 min), Maximum Connection Duration, and Daily Reset if they fire too often.
Check the connected-client RTT / packet loss stats for underlying network trouble.
Unexpected test card in Orbit
Work down the override hierarchy:
Turn off the global "Force Test Card (All Connections)" — check this first.
Turn off "Start New Connections with Test Cards".
Check the per-code Test Card toggle for that client's access code.
If test cards persist with everything off, click Restart Orbit (in the Orbit settings panel) to re-establish the pipelines.
Dependency / firewall issues (general)
Open the Dependencies window (About → System Dependencies & Firewall).
Confirm NDI Runtime and GStreamer both show Installed (green).
On Windows, click "✓ Fix Automatically (recommended)" and approve the single admin (UAC) prompt, then run "Check Firewall Rules" to confirm both rules are Allowed. Cancelling the prompt does nothing harmful.
Rule out a VPN / kill-switch
A VPN or kill-switch (e.g. NordVPN) or macOS Local Network privacy can silently block both local NDI discovery and local/outbound SRT, with no warning in Pulsar. Always rule it out when something "works on another machine but not this one":
Temporarily disable the VPN / turn off its kill-switch and retry.
On macOS, check System Settings → Privacy & Security → Local Network and allow Pulsar.
Applies to both macOS and Windows.
Tips & gotchas
Skipped, not failed. An unconfigured output is skipped on Start with a toast — the rest of the batch still starts. Watch for the toast.
Reach dependency status via About → System Dependencies & Firewall.
NDI Firewall Protection is also a cause. When it's on (macOS), other machines genuinely can't see this machine's NDI — separate from the VPN cause.
A VPN / kill-switch is invisible to Pulsar. It can block both NDI discovery and SRT. Always rule it out for "works elsewhere but not here."
macOS permissions don't re-prompt. If you deny Screen Recording or Camera once, grant it manually in System Settings. FILE playback from protected paths also needs Full Disk Access, after which you must restart that stream.
Orbit "Allow Remote Access" may need an app restart to take effect.
Each output is either SRT or NDI — not two SRT outputs. SRT source rows can use Orbit too.
NDI Audio Level Pad ranges −40 dB to 0 dB.
Related pages
Introduction
NDI source · Screen / Camera / Test Card · File source · SRT input · Unreal Engine
Outputs (SRT / NDI)
Orbit streaming
Settings and configuration
Glossary