Expected response on ssdp:discover

[Raf]

Hi,

My (wireless subnet) control points are (still) struggling detecting my (wired subnet) MinimServers.

I am running 2 MinimServers (basically to support a different approach towards classical music tagging) on a Debian 9 64bit server, having http.port 9710 & 9711 and ohnet.port 9720 & 9721 respectively.

The router/firewall is a Sophos XG. The main switch is a Zyxel GS2210 24 ports. Both are running latest firmware.
The control points are mconnectPlayer (IOS) and BubbleUPnP (Android)

I enabled multicast forwarding for the multicast IP 239.255.255.250
1- from the wired minimserver IP to the wireless subnet
2- from the wireless control point(s) to the wired subnet

For now I disabled IGMP snooping on the switch, but that did not make a difference.

I took some network interface dumps on the server (tcpdump -i eth0 -w <file>).

When I restart a minimserver (MinimWatch) (and rescan in the control point) it becomes visible in the control point, as at that time an alive message is send

NOTIFY * HTTP/1.1
---------------------
HOST: 239.255.255.250:1900
SERVER: Posix/200809.0 UPnP/1.1 ohNet/1.0
CACHE-CONTROL: max-age=1800
LOCATION: http://<ip mediaserver>:9720/<uid>/Upnp/device.xml
NTS: ssdp:alive
...

When I scan from the control points, I see request coming in on the server (below is triggered from mconnectPlayer)

M-SEARCH * HTTP/1.1
--------------------------
HOST: 239.255.255.250:1900
MAN: "ssdp:discover"
MX: 3
ST: urn:schemas-upnp-org:device:MediaServer:1

But I expected a reply from the mediaserver towards this "discovery" request and I don't see them in the dump.

What would have been the expected response ?

Kind regards - Raf