monitor window Linux raspberry pi 4 won't see Sacn universes

[djb1972]

Hi There,

I have some issues with the monitor window , it doesn't display all the Sacn universes that send to the app .(64 )

but sometimes a few universes but not all I send , and with gaps in universes

but when I switch form Sacn to ArtNET (chamsys pc ) then I see all my 64 Artnet universes in the monitor

Is it network thing or something else

Chamsys 192.168.2.121 255.0.0.0
Rasp pi 192.168.2.250 255.0.0.0

on linux raspberry 4 , DMXrouter 1.7.1

with regards

[fiverecords]

Hi! This is a Linux kernel limit, not a DMXRouter issue. sACN uses multicast (one group per universe), and Linux defaults to a maximum of 20 multicast memberships per socket. With 64 universes you're hitting that limit — the extra joins fail silently, which explains the gaps. Art-Net works fine because it uses broadcast, not multicast.

The fix is simple — increase the IGMP limit:

Temporary (until reboot)

sudo sysctl -w net.ipv4.igmp_max_memberships=256

Permanent

echo "net.ipv4.igmp_max_memberships=256" | sudo tee -a /etc/sysctl.conf

After that, restart DMXRouter and all 64 sACN universes should show up. Let me know if that fixes it!