I'm trying to do what I think is the simplest possible multicast test:

Server on Ethernet LAN steams multicast udp packets to 224.0.0.1.
Ethernet is bridged to AP on RB411.
Clients are iPhones associated with RB411 AP.
iPhones are running test program that listens on 224.0.0.1 via wifi.

The iPhones successfully get an IP address via DHCP. The DHCP service is running on a separate server on the Ethernet. This shows that the Mikrotik bridge function is working as usual.

PROBLEM:
The statistics on both ends report that it takes several seconds to deliver a single multicast packet. Most (almost all) transmitted multicast packets never reach any of the iPhones.

I then swap out the Mikrotik router and replace it with a linksys wireless router, using the same topology, and the source now delivers multicast packets to iPhone receivers at a few megabits/second.

Note that there is no WAN involved. There are no routers. The RB411 is just bridging. The linksys device is connected via it's Ethernet port on the LAN side, which is also bridged to its AP.

I'm running ROS 4.11 without multicast package. Since this is a single subnet with no routing, I don't believe any multicast protocols are needed.

Am I doing something wrong? What is there to configure on the RB? It's just a bridge with 2 ports - the Ethernet and the AP.

As another data point, if the address is changed from 224.0.0.1 to 192.168.1.x, the unicast data stream runs at several megabits/second through the RB to the iPhone clients.

Can anyone shed some light on this? Do I need any special configuration to make this work? If so, why?

Ok, here are some more test results.

I've determined, via torch, that packets are leaving the AP. I set up another RB411 as a client and wiresharked the packets coming off the ethernet of that client. The 244.0.0.1 packets are being received by a ROS client, but not by an iphone.

I replaced the RB411 with a cheap linksys AP and the iphone had no problem receiving the multicast packets.

There is something about a Mikrotik device that prevents iPhones from seeing the multicast packets, while a cheap linksys works just fine.

This application has the potential to sell a few thousand Mikrotik devices, so I'm rather anxious to get this working.

Any suggestions would be appreciated, including debugging advice.

Problem found. ROS v4 and v5 do not support wifi multicast. This feature was "lost" after ROS v3.

For more details, click here.