Multicast/SSDP not working (on VLAN interface)

[Andreas Scherrer]

Dear List

I was unfortunately unable to find a way to search this mailing list's 
archive; so please bear with me if the question was answered before.

My goal is to have DLNA clients (VLC, Heos music system, ...) in 
multiple networks discover a MiniDLNA server.

The server shows up in VLC when it starts (or is restarted) after VLC is 
running. If the server is already running when VLC is started, VLC does 
not detect/find the server.

Very much like this source states:
https://sourceforge.net/p/minidlna/bugs/94/#8c8f
I suspect a problem with the M-SEARCH messages the client is sending.

Using tcpdump on the interface where M-SEARCH from VLC are coming in, I 
can indeed see the packets/messages arrive (they are sent from the 
client to 239.255.255.250). So it is is not a router or switch or 
whatever blocking the packets.

Now, if I (manually) add a static route for 224.0.0.0/4 via the 
interface the M-SEARCH messages are coming in, everything starts to work!

route add -net 224.0.0.0/4 -iface re1.32

The (main) problem here is that I have multiple networks with clients in 
them. So a static route does not REALLY solve my problem.

Also I do not (yet?) understand why the route should be required.

What I see is that ifmcstat -f inet -i re1.32 does not list a membership 
for 239.255.255.250 when it is not working, but does list the membership 
when it is working...

So I suspect that "something" is dropping the M-SEARCH packets for some 
reason after they are received. And I cannot get rid of the feeling that 
it has something to do with the fact that the incoming interface is a 
VLAN interface...
My first guess, anti spoofing, seems not to be the problem (I am using 
ipfw and "not antispoof in" but that does not seem to drop any traffic).

Do I miss something obvious or can someone point me in the right direction?

VLC v2.2.8 is running on Mac OSX 10.12. MiniDLNA v1.2.1,1 is running on 
FreeBSD RELEASE-11.1.

More information can be found in the FreeBSD forum [1].


Thanks heaps
andreas

[1] 
https://forums.freebsd.org/threads/minidlna-not-discovered-multicast-issue.64947/