Orbi 37x and Local Network Control Block (224.0.0/24) multicast

Does everything work if all is connected to the RBR if RBS are turned OFF temporarily as a quick test? 

How is the RBR configured for AP mode? Dynamic or Static IP address? 

RBR connected to host router using it's WAN port? 

Brand and model# of the host router the RBR is connected too? 

For AP mode, ALL should be flowing thru the system with out being blocked. There maybe some configuration needed at the host router to help effect that. 

Someting to contact the music application mfr about and see if there are any specific configurations needed there. 

FURRYe38 we exchanged already about the hourly WiFi disconnect in RBS, still no progress from Netgear on this front and still hourly disconnects on my side.

• I have tested against RBR, as well as against RBS, i.e two hosts connected to the same Orbi kit sending multicast packets to 224.0.0.234, this traffic does not go through.
• RBR is having a static IP address, no DHCP here.
• RBR is connected to a french FAI router (Freebox Delta) which is multicast aware (this is the way their TV stream is distributed), but not applicable here I guess as we ar in the Local Network control block space according to IANA.org
• Agree that ALL should be flowing thru the system, particularly when both are connected to the same RBS, I don't see here the need for the FAI router involvement, particularly for a local network only traffic. I have a single IP subnet.
• The music app uses Snapjack for this purpose, there is no special requirement but allowing multicast to 224.0.0.234 for discovery purpose.

I agree with FURRYe38​ that the host router is an important part of the configuration.  With the current setup, does any of the data flow through the host router?

The host router carries all traffic he has to carry, i.e intranet/internet traffic.

Host A & B are RPIs or MacOS depending on the tests I carried on.

Host A & B are WiFi connected to the same Orbi kit (being RBR or RBS depending on the tests I carried on)

Host A can communicate with host B in my LAN as well as other hosts in my LAN using many network protocols

Host B can communicate with host A in my LAN as well as other hosts in my LAN using many network protocols

ARP table of host A shows host B MAC address

ARP table of host B shows host A MAC address

Host A and host B can communicate with any Internet host through the FAI router, from which they get their IP address via DHCP

Host A multicast packets sent to 224.0.0.234 are not received by any hosts in my LAN, including host B

Host B multicast packets sent to 224.0.0.234 are not received by any hosts in my LAN, including host A

If Host A & B are connected to the same Netgear switch, itself wired to a RBS, then they can see multicast packets from each other

Update:

Based on StephenB​  comment about "Blocking of unknown multicast addresses" , i ran the following test.

Setup

• Host A RPI  Debian GNU/Linux 13 (trixie) Wifi connected to RBS 1
• Host B RPI  Debian GNU/Linux 13 (trixie) wired to Netgear Switch wired to RBS 1
• iperf tool installed on both host A and host B

Test Scenario

• Join Host A to mcast group 224.0.0.252 (registered as Link-local Multicast Name Resolution) and use Host B as client to send datagrams to this group address: SUCCESS - Host A receives the datagrams
• Join Host B to mcast group 224.0.0.252 (registered as Link-local Multicast Name Resolution) and use Host A as client to send datagrams to this group address: SUCCESS - Host B receives the datagrams
• Join Host A to mcast group 224.0.0.235 (part of unassigned mcast block according to IANA) and use Host B as client to send datagrams to this group address: FAILURE - Host A DOES NOT receive datagrams
• Join Host B to mcast group 224.0.0.235 (part of unassigned mcast block according to IANA) and use Host A as client to send datagrams to this group address: SUCCESS - Host B receives  datagrams

My conclusion: 

• These test are consistent with my first observations
• When listening server is Host A and Host B is the sender, only datagrams to 224.0.0.251 and 252  groups are going through, many other mcast groups i have tested in the 224.0.0.1/24 block don't go through. Note: I have not tested all of them, but many well known, including IGMP 224.0.0.22 don't go through.
• When listening server is Host B and host A is the sender, all mcast groups I have tested are going through
• It is obvious that there is a difference between RBS/RBR ethernet port traffic management and wireless management
• All tests I have done are reproducible