This article only applies to users using sACN
If you reboot or move a Sidus Four, Stardust, or even Blackout and your entire set suddenly goes black, you may be seeing expected behavior from your network’s IGMP Snooping and IGMP Querier settings.
This most commonly happens when:
Unplugging a transmitter from PoE, moving it, and plugging back in
Power cycling a transmitter
Rebooting your console, especially if it boots faster than your network refreshes
Switching ports on a managed switch
What’s Actually Happening?
When you use sACN multicast, your switch keeps a table linking:
Each device’s MAC address
The switch port it’s on
The multicast universes it subscribes to
This table is maintained using IGMP Snooping and periodically refreshed by an IGMP Querier.
The issue:
If a device reboots or moves ports, the switch may still think it lives on its old port for up to a few minutes.
Many managed switches (especially compact show switches) default to around a 2-minute IGMP query interval, which means:
sACN multicast continues being routed to the old location
Your Sidus Four / Stardust / console receives no data
Fixtures sit at zero
After the next IGMP refresh cycle, everything suddenly starts working again
In other words:
Your devices are ready long before the switch updates its routing.
Why the Switch Doesn’t Correct It Immediately
The switch may not overwrite an existing IGMP entry if the same MAC address is already registered on another port.
IGMP Snooping tables can stay “stale” until timeout.
Some managed switches (like the NS8 and other similar models) have firmware limitations where Snooping can’t fully be disabled, even if the UI suggests it can.
This can impact both transmitters and consoles — anything generating or routing multicast traffic.
How to Prevent Your Show From Going Dark
1. Shorten the IGMP Timeout
Adjust your switch settings so stale entries clear faster.
A common safe setup:
IGMP Query Interval: ~60 seconds
Membership Timeout: ~30 seconds
This keeps the multicast routing fresh while avoiding premature clearing.
2. Use Only One IGMP Querier
If your system has multiple smart switches, only one should be the querier.
Multiple queriers can cause unpredictable multicast routing updates.
3. Reconnect Devices to the Same Port When Possible
Keeping your Sidus Four, Stardust, or console on the same port avoids stale routing issues entirely.
4. Be Aware of Switch Firmware Quirks
Some managed switches (like the NS8 and similar compact gigabit options):
May continue snooping even when disabled
May not refresh routing tables predictably
May take longer than expected to clear IGMP entries
If this matches your network, consider:
Enabling both Snooping and Querier and tuning the refresh intervals, or
Using a different switch until firmware updates resolve the bugs
Summary
If rebooting or moving your Sidus Four, Stardust, or Blackout Lighting Console causes your set to go dark temporarily, the root cause is almost always:
The network switch is still routing sACN multicast to an old port until the next IGMP refresh cycle.
Adjusting IGMP settings or using an unmanaged switch for smaller networks will eliminate the issue.