Devices are not discovered
KLSTR.ctrl finds devices in three different ways, and each one fails for its own reasons. KLSTR.one fixtures announce themselves on the KLSTR.one interface over IPv6. Art-Net nodes answer the ArtPoll that KLSTR.ctrl sends on the Art-Net interface over IPv4. RDM fixtures and KLSTR.nano modules appear only after RDM discovery has run on a node's DMX ports. Start with the section that matches what is missing.
First checks
- The right interface. Hover over KLSTR.one or KLSTR.nano in the header to see which interface KLSTR.ctrl listens on. A red dot means no interface is selected, an orange dot means the link is down. With a remembered interface, KLSTR.ctrl reconnects to the interface from last time, which may not be the one your lighting network is on today.
- Demo mode off. In demo mode, KLSTR.ctrl shows demo devices only. Select a real interface instead of DEMO.
- macOS permission. If a Local network access is blocked message appears, or the Health Check tab shows system › localNetwork › denied, the computer blocks KLSTR.ctrl. See macOS blocks local network access.
- A wired connection. Use a cable rather than Wi-Fi for the lighting network. Many Wi-Fi networks drop or delay multicast and broadcast traffic.
KLSTR.one fixtures don't appear
A KLSTR.one fixture sends a short announcement (a heartbeat) twice a second to the multicast
group ff12::c8:c8, UDP port 40000, from its IPv6 link-local address (fe80::…).
KLSTR.ctrl listens for it on the selected KLSTR.one interface. A fixture that has been silent
for about 10 seconds is shown offline.
| What you see | Likely cause | What to do |
|---|---|---|
| Your interface is greyed out under No IPv6 link-local address | IPv6 is off on that interface | Click Enable IPv6 on all interfaces in the interface dialog, or switch IPv6 to automatic in the operating system's network settings. See Connect KLSTR.ctrl to your network |
| The dot is green, but no KLSTR.one fixture appears | The fixtures are on another network segment than the selected interface | Link-local multicast doesn't pass routers. The computer must be on the same Ethernet segment (the same switch network and VLAN) as the fixtures. Select the interface that is |
| The fixtures are on a tagged VLAN | The physical interface only carries untagged traffic | Create a VLAN interface for the lighting VLAN in the operating system, or patch the computer into an access port of that VLAN. Then select that interface in KLSTR.ctrl |
| Fixtures appear, then all go offline at once | The cable was unplugged, the link flapped, or the computer slept | KLSTR.ctrl rebuilds its connection by itself once packets flow again. If they stay offline, select the interface again |
| A fixture you just connected never appears | It is still starting up, or its own network port is not linked | Wait for it to finish booting, then check its cable and the switch port |
| Only some fixtures appear | The switch filters IPv6 multicast (MLD snooping without a querier), or the fixtures sit behind another switch that drops it | Allow IPv6 multicast between the ports, or switch on an MLD querier on the switch |
The IPv4 address of the KLSTR.one interface doesn't matter for finding KLSTR.one fixtures. They are found and reached over IPv6 link-local only.
Art-Net nodes don't appear
KLSTR.ctrl sends an ArtPoll every 2.5 seconds to the broadcast address of the Art-Net interface's IPv4 subnet, and lists every node that replies.
| What you see | Likely cause | What to do |
|---|---|---|
| No node appears | The Art-Net interface's IPv4 address is in another subnet than the nodes, for example 192.168.1.10/24 against nodes in 2.x.x.x | Give the interface an address in the nodes' subnet, then select the Art-Net interface again |
| No node appears, and Discover Art-Net is in the bottom toolbar | Manual ArtPoll is on, so KLSTR.ctrl polls only when you ask | Press and hold Discover Art-Net, or switch Manual ArtPoll off in the Art-Net interface dialog |
| One node with an unknown or wrong IP address is missing | It is outside the interface's subnet | Tick Limited BC in the Art-Net interface dialog to find it, give it a proper address in its own settings, then switch Limited BC off again |
| A factory-fresh Showtec NET-2/3 node never appears, although its address is in your range | Until its settings have been saved once, this node answers only an ArtPoll sent straight to it, to 255.255.255.255, or to the broadcast address of its own subnet mask. With another mask on your interface (for example a /16 against the node's /8), it ignores the poll | Tick Limited BC, or open the node's web interface and save its settings once (Apply). After that it answers normal polls for good, also after a power cycle |
| The node appears, then goes offline after about 15 seconds | Its replies stop reaching KLSTR.ctrl | Check the firewall (below) and the cable. With Manual ArtPoll on, a node is only rechecked when you poll |
| An ELC (dmXLAN) node appears, but RDM to it fails | ELC-Net is blocked, or the node needs plain Art-Net RDM | Allow UDP port 6517. If that doesn't help, switch off Use ELC-Net for ELC nodes in User settings › NETWORK on advice from KLSTR support |
A change you make in User settings › NETWORK applies only when you select the Art-Net interface again with KLSTR.nano › Select Art-Net interface (press CmdShift A on macOS, Ctrl ShiftA on Windows). The Limited BC and Manual ArtPoll checkboxes in the interface dialog itself apply straight away. See Settings: Network.
Fixtures behind an Art-Net node don't appear
| What you see | Likely cause | What to do |
|---|---|---|
| The node is there, but no fixture | RDM discovery hasn't run on its ports yet | Choose KLSTR.nano › RDM › Discover, or click the discovery icon in the node's box. See Discover devices |
| A warning sign in the node's box, and discovery finds nothing | RDM is switched off on the node | Click the warning sign to switch RDM on, where the node supports it, or switch it on in the node's own settings |
| Discovery finds nothing on a port | The port is input-only, the node is disabled, or Skip discovery on bidirectional ports is on and the port is input and output | Set the port to output on the node, enable the node, or switch the setting off |
| Fixtures on one port all turn offline after a discovery | The node sent no device list within 15 seconds, or the DMX line is broken | Check the DMX line, terminators and splitters, then discover that port again |
| The node is found but its fixtures never show up, or show up incomplete | The node doesn't follow the Art-Net specification: it doesn't report RDM support, or sends its table of devices late or in pieces | Switch on Workaround Art-Net quirks (User settings › NETWORK, with Advanced settings on), select the Art-Net interface again, and run RDM discovery again |
| Fixtures behind a Showtec NET-2/3 node keep switching between online and offline | The node doesn't pass on the queued-message requests KLSTR.ctrl uses to check that RDM devices are still there | Known issue, no workaround in KLSTR.ctrl yet. See the note below |
| Fixtures are missing their DMX modes or sensors after a large discovery | Some RDM replies were lost | See RDM data or sensors are missing |
Firewall and security software
KLSTR.ctrl needs these connections between the computer and your devices. Allow them in the firewall of the computer (on Windows, allow KLSTR.ctrl on private networks when the system asks) and in any network security software:
| Traffic | Protocol and port | Direction |
|---|---|---|
| KLSTR.one heartbeats | UDP 40000, multicast group ff12::c8:c8 (IPv6) | From the fixtures to the computer |
| KLSTR.one device API | TCP 5561 and 8889 (IPv6 link-local) | From the computer to the fixtures |
| Art-Net, including ArtPoll and RDM | UDP 6454 (IPv4), the Art-Net standard port | Both ways, including broadcast |
| ELC-Net, for ELC nodes | UDP 6517 (IPv4) | Both ways |
Another program on the computer that uses Art-Net (a console or visualiser software) can also hold on to the Art-Net port. If nodes stop appearing while such a program runs, quit it and select the Art-Net interface again.
Related
Written for KLSTR.ctrl 1.2.0 (a0df909) · Checked 1 Oct 2026