It looks like UPnP multicast discovery announcement packets on all Comcast SMCD3GNV routers are blocked, which causes devices like the HDHomeRun to not work. If you have one of the Silicon Dust HDHomeRun models, you will notice that it will not work or stop working after 30 minutes or so. Even Silicon Dust, which is the company behind the HDHomeRun, posted information saying that Comcast-provided SMCD3GNV routers are broken: http://www.silicondust.com/support/hdhomerun/testfai/upnp_multicast_recv/
The post specifically mentions: "Comcast-provided SMCD3GNV routers are broken and will block this traffic regardless of what configuration options are set."
I did verify that this is indeed the case (HDHomeRun stops working after 30 minutes). Is this a known issue and is there any chance that this will get fixed in a future SMCD3GNV firmware update?
It appears to me the upnp doesn't work at all for this router. I have a ps3 and xbox360. Both of which report upnp to be disabled even though it is clearly enabled on the router. This in effect makes setting these devices up to their fullest potential a royal pain in the a#@. And this 'issue' has been present since this router was made available some years ago. Comcast just doesn't appear to care about this, being in their view few people use this functionality. I've heard that many people are purchasing their own wireless router and using the SMC router in bridge mode. And to put it in bridge mode, you have to contact comcast, being this option is restricted to us lowly customers. WHY comcast couldn't simply use the firmware that SMC normally provides rather than tinker with it and in effect cripple it is beyond me.
Does anyone know if this UPnP issue is specific to the SMCD3GNV router, or are all Comcast router models afflicted with this issue? If other Comcast router models do not have this issue, perhaps I can just exchange the SMCD3GNV for a model where UPnP actually works.
Based on everything I've read, the best solution is to spend more money and invest in your own wireless router and have the Comcast SMC (dare I even call it a router) put it in bridge mode. Comcast to my knowledge has never responded EVER to this issue (at least on the forums). Which pretty much confirms that they know it's screwed up and they simply don't care because the vast majority of people aren't affected. Typical monopolistic attitude from your typical big corporation. I'm going to call them and see what they say... I'd at least like them to admit that there is an issue here. But of course their silence on these forums implies guilty as charged.
Chromecast is also completely effed up by this incompatibility, which is another likely reason why Comcast is blocking it and leaves it unfixed. I agree with the statement by the prior poster that it is typical MONOPOLISTIC practices of a company that is TOO BIG and stifling competition as well as innovation.
Comcast is actually in the process of rolling out a new modem with wireless gateway that takes care of this and the other problems associated with it. you need to remember comcast is a big company and cannot change at the drop of a pen. when the get equipment like this they are contracted into it for so long and buy so many units that it isnt possible just switch. But i have the new gateway and have no problems with chromecast anymore