I just got a Spark Pro as a video input device for my Digistar 6 fulldome Planetarium system from Evans&Sutherland (E&S). This system has 21 computers, where one is the Master (DSHOST) and 20 are Graphics processors (GPs).
The Spark is connected to the Digistarīs NonRealtime Network (as proposed by E&S) which is "xxx.xxx.2.xxx". Multicast is enabled. To get a full image in our 21m Dome, all 20 GPs need to get the image and the Host manages the alignment and blending. The Host itself shows the image in a preview window.

We set it up and got an image on GPs 2-20, but not on the Host and GP1, which also is our Audio-Computer. Therefore, the Host and GP1 are also connected to our Dante-Network which is "xxx.xxx.5.xxx". When I change the network adapter settings on those two machines and just disable the Dante (.5) network, all is working as expected. As soon as I enable Dante again, those two computers do not get the stream, but all others keep on working. On Dante, IGMP snooping is enabled.

Which settings in Dante could cause that issue?