Multicast Setup Confusion

I have been searching for some information about setting up multicast but seem to be comming up short.

What I have is 10 slave units set up in OTAA mode and in Class C. They have no issues sending messages or receiving messages individually. They also have some multicast paramaters and share the same mulNwkSKey, mulAppSKey and multicastAddress.

On Chirpstack these devices are part of a Multicast Group.

I then have another device (letc call this masternode) set up in APB and Class C.
nwkSKey, appSKey and devAddr are set to be the same as the mulNwkSKey, mulAppSKey and multicastAddress used in the group.

It seems that none of the slave units are hearing the message’s being transmitted from the masternode

Or do i have to set all of the units up in APB mode?

The goal is that mostly all the slave units will receive start/stop messages from the masternode however each one individually may also receive a message from a web interface from time to time so they need to have their own addresses.

Thanks in advance for any sugestions or pointers on this.

I’m not sure if I understand this. Please note that multicast is not a node to node communication. Multicast can be used so that a NS can send a downlink to multiple devices.


Also interested in multicast message, but I’m not sure if this is possible with OTAA devices or only for APB ones.