Hi @Bhavya443
Welcome to the community!
In FreeRTOS-Plus-TCP v4.0.0 there is a very limited support of multicast right now.
Multicast can work on the same local subnet without routing, but working with VLANs and different subnet requires routing/IGMP support, which is currently not present on FreeRTOS-Plus-TCP v4.0.0.
Multicast support for IPv4 and IPv6 is in our roadmap, you can check forum issue , github issue for more details.
You can also check the roadmap here.