IMNSHO, it's a given that Netgear firmware is a PoS (a unit of future compost). Why it is so bad, I don't know - I have gone through multiple routers and Linksys, Motorola, D-link, Belkin together have caused me less headaches with NAT and port mapping than Netgear does. Must be something with their developers but i don't know anything other than the software is written in India (and Linksys fw was being done in Taiwan). OTOH, Netgear are solid as hardware - i recommend their powerline networking and probably anything that has no complicated software in it. That's my personal unscientific opinion.
Now back to the problem at hand. I skimmed over a manual for WNR3500 (
http://www.upc.nl/pdf/upc-handleiding-n ... nr3500.pdf) and there is nothing helpful there on broadcast/multicast/SSDP there. There is option about UPnP however (see 5-12) - try enabling it and testing that way, even if UPnP when we speak routers is used to map internal/external ports, it does use SSDP and may as side effect fix your problem, so try it.
Why is SSDP so problematic over WiFi - turns out multicast/broadcast of datagrams have to be emulated by the router - when host sends packet, router has to forward it separately to each other known host - this in contrast with the approach in Ethernet where all hosts can just listen for it on the common media. Because of that special handling, turns out there are multiple routers in which multicast over WiFi is broken.
PS. somebody else's voes:
http://forum1.netgear.com/showthread.php?t=68257