Dual-WAN and multicast
I'm not sure if this qualifies as a bug or it's expected behavior, but it took me forever to figure out what was going on…
I have two WAN interfaces but I'm not using load balancing. I have firewall rules set up to direct traffic from specific internal hosts to one or the other WAN interface (i.e. source 192.168.1.2 destination * gateway WAN2). When I do this, the miniupnpd service is no longer able to receive multicast SSDP requests from that host. If I change the rule to (destination !220.127.116.11/8) then miniupnpd starts seeing the multicast packets again.
That's expected behavior, it's doing exactly what you told it to do because it matches that rule, which tells it to forward to which ever gateway.
OK thanks.. It just seems a little strange that services running on the firewall will still "see" broadcast traffic (DHCP, etc) with the rule in place, but not multicast. I would have thought it should always see both regardless of where they're being forwarded. In any case, I ended up adding a rule "source * destination 18.104.22.168/8 gateway *" at the top of the list which resolved the issue for all of the devices on the network.