Nomad on Mac Mini intermittently stops sending sACN

I was able to reproduce the problem repeatedly at startup of the Nomad software, universe 3 would come up fine but universe 1 would not.  Wireshark on the Mac Mini showed the universe 1 multicast packets but on a different laptop connected to the same switch only the universe 3 multicast packets were showing up.

I changed the configuration to use unicast instead of multicast, which has reduced the amount of traffic on the network considerably, so we'll see if that makes a difference.

I was able to reproduce the problem repeatedly at startup of the Nomad software, universe 3 would come up fine but universe 1 would not.  Wireshark on the Mac Mini showed the universe 1 multicast packets but on a different laptop connected to the same switch only the universe 3 multicast packets were showing up.

I changed the configuration to use unicast instead of multicast, which has reduced the amount of traffic on the network considerably, so we'll see if that makes a difference.

Switching to Unicast solved the problem.  I ran a full rehearsal last night with no sACN drops, where the night before it was dropping every 30 minutes or so.

Great that you got it to work!

This sounds a bit like your switch is struggling with multicast or with the load. 4 universes shouldn't be a problem for anything less than 10-15 years old, but the culprit could be the configuration of the switch.

This does sound like a switch issue. Out of curiosity, is there a TP-Link switch on the network? I’ve encountered an identical situation numerous times where sACN output intermittently drops. Every time that I’ve encountered it, there was a TP-Link switch in line between the source and receiver. And every time the problem was solved by swapping out the switch for another brand. 

I suspect an issue with the IGMP Snooping capabilities or capacity of the switches. Using Unicast also explains why this would fix the issue as the switch isn’t having to route Multicast packets to your receiver.

Yep - in this case a TL-SG1005P, the only switch connecting the Mac Mini to the Pathports.  I figured since it's unmanaged it would leave the IGMP alone - I guess that was a bad assumption.  I'll try it with a Netgear switch and see if the same thing happens, although I think I'll stay with unicast anyway since it's much more efficient and not that much effort to configure.  Thanks for the pointer!