Multicast forwarding on UTM

Hi there,


I have a testbed with a Sophos UTM where there are two networks connected (each on a interface of the UTM).

N1: (UTM IP:
N2: (UTM IP:

As both networks are known to the  UTM, there was no need to define a static route from one network to the other.

Network traffic is working fine between both subnets. (Unicast) packets are forwarded from N1 to N2 and vice versa.


I then added three hosts on one subnet (N2), where one is the sender of multicast packets and the other two are the receivers. is sending multicast packets (using iperf) to the IP address and bind to and are able to receive the packets.

So far, so good.

I've then added a host to N1 ( which should also receive the multicast packets.
Unfortunately, it does not. I do not have a clue, why.
I've also followed various documentation pages and howtos (also on the Sophos website), but no one did work.
I've configured multicast interfaces in the multicast routing section as well as a multicast router (I've tried both IP addresses of the UTM and wanted to use the UTM as multicast router).
I even added routes as the documentation reads that one needs to add multicast routes if multicast packets should be forwarded between subnets (is that really necessary in this scenario).


No one of my tests allowed me to receive broadcast packets on subnet N1.

Does anyone have a clue as to why?
Is there some documentation or howto available that also works for this scenario?

Best regards,

  • Hi Bob,

    as this answer came a year after my question, we did not continue that project in that way.
    Instead we changed cabling in the building to have the necessary networks available where they were needed and people now have additional PCs where they can watch the video cameras.
    What Le suggested might be really good, but I did not have the time nor the demand to try it out.
    Unfortunately, the answer came too late for me.

    Even our partner said that they did not manage to do that yet and that it is difficult with Sophos UTM. As we needed a solution, we had to find an alternative...


  • @Thomas
    Sorry to hear about your difficulty and my reply is too late to help you (my apology)
    Multicast on UTM works fine as there are customers using it for video applications.
    Hopefully next time (and I am sure) that our support will help you out. Thanks for your understanding and patient.

    Thanks so much for your expert answers and I learn so much from your comments/suggestions. It is very much appreciated!