How to run DMX over Ethernet without putting show traffic on the wrong network

Separate the show LAN

Art-Net broadcast and sACN multicast will happily disturb cameras, POS terminals and guest Wi-Fi if they share a switch. Use a dedicated NIC, a VLAN, or an unmanaged switch that only lighting devices plug into.

Phones running a control surface can sit on a different network. Do not treat Wi-Fi as the DMX transport. The rule is: copper for universes, wireless for humans who can survive a dropped packet.

A minimal good topology

Lighting PC → gigabit switch → Ethernet nodes → XLR to fixtures. That is the whole drawing. Add a second NIC on the PC for internet and file transfer so the show interface never needs a default gateway.

Give the PC and each node a static IP on the same subnet. Write a tiny table: name, IP, universe, port. Tape it inside the rack. DHCP is how a node becomes 192.168.0.47 on Friday and 192.168.0.63 on Saturday.

If you must share a managed switch with other departments, ask for an isolated VLAN and IGMP snooping. Do not “just use VLAN 1” because it already works for printers.

Addresses, ports and firewalls

Put the controller and the nodes on the same subnet. Allow UDP 6454 (Art-Net) and the sACN UDP ports your nodes expect. OS firewalls often block the first show of the night. Windows “Public network” is a frequent villain.

Confirm the output interface. Laptops with Ethernet dongles, Thunderbolt docks and VPNs present multiple adapters. Sending Art-Net out the Wi-Fi NIC is a classic silent failure: the visualiser on localhost looks perfect.

What not to share the switch with

Dante, NDI, and lighting multicast on the same cheap switch without QoS is a lottery. If audio-over-IP is in the room, give lighting its own switch or a dedicated VLAN with a grown-up configuration.

Guest Wi-Fi access points bridged onto the show VLAN will wander. Keep APs off that VLAN. The DJ’s phone does not need to subscribe to universe 12.

A five-minute pre-show check

Ping the nodes. Confirm the output NIC. Confirm universe numbers on sender and node. Open a DMX viewer on the XLR or a known fixture at address 1. Wiggle one channel. Then bring up the rest of the patch.

If something is dark, do not start by rewriting the whole show file. Work the list: cable, node universe, PC interface, firewall, start address.

A packing list for a small room

One unmanaged gigabit switch that never leaves the lighting rack. Two short Ethernet jumpers and one long run you have already tested. Gaffer labels for every node IP. A USB-C Ethernet dongle that is not also the office VPN dongle.

A printed /24 table: .10 PC, .20 node A, .21 node B, .30 spare. Leave .1 for a router you should not need. If someone plugs a consumer router “for internet,” it will hand out 192.168.1.x and the show IPs vanish. That is why the show NIC has no gateway.

Photograph the rack once a month. When a cable is moved, you will thank yourself. Network problems that “only happen after cleaners” are usually a replugged uplink into the office switch.

Internet is a separate problem

The lighting PC may need Cloud sync or a download on Monday. That traffic belongs on the second NIC or a dock port that is not the show LAN. Never set the show NIC’s gateway to “whatever DHCP said” on a venue that also serves guests.

If you only have one NIC, unplug the uplink to the building before doors. Updates can wait. Broadcast lighting cannot share a surprise Windows update and a 40-universe blast on the same cheap switch without someone crying.

Wi-Fi myths, one more time

Someone will suggest “just use the venue mesh, it is gigabit.” Mesh backhaul is not a show LAN. Phones roam. Access points reboot. A lighting universe that disappears for two seconds is a blackout, not a buffering spinner.

Use Wi-Fi for a control surface you can survive losing. Use copper for every universe that moves a motor or a strobe. If the venue will not give you copper, reduce the automated layer and keep a human on a local USB DMX path as the last resort.

Write that rule on the inside of the rack door. Arguments at 23:00 go better when the policy already exists.

Related

• What is Art-Net? →
• Small club lighting network →
• Patching →