"If IGMP snooping is enabled on a switch, or more commonly a wireless router/switch, it will interfere with UPnP/DLNA device discovery (SSDP) if incorrectly or incompletely configured (e.g. without an active querier or IGMP proxy), making UPnP appear unreliable."
I'm having issues with SSDP on my Philips Hue bridge and I have ZyXEL smart switches and Mikrotik routers with IGMP proxies (configured for IPTV), and I'm not sure how to make it all work properly.