Wondering if anyone is aware of an add'l item to verify related to ones router when using Mezzmo? I have done the following:
•Check your router is not set to use IGMP snooping or IGMP Proxy and turn it off. Reboot your router and PC after making any changes.
•Check your router does not have built-in UPNP turned on, or a built-in firewall turned on. Try turning these settings off. Reboot your router and PC after making any changes.
•Check your router is not set to use Jumbo Frames and turn it off since your DLNA device may not support Jumbo Frames. Reboot your router and PC after making any changes

In addition, I've reinstalled fresh Mezzmo application, 100% verified Windows firewall is off AND made sure Norton Internet Security 2013 firewall is off (even though both have the proper rules set up for Mezzmo). But yet I am still getting an "unable to access media" error from most Direct TV boxes. As mentioned in an older post, the set up worked fine for over a year and for a while I thought it was Norton, but with it shut down not aware of anything else other than the router. I do know the router updated firmware w/out my knowledge around the time this all started. I have a Qwest Q1000. All device profiles look fine in Mezzmo, allowed to access, and have correct IP addresses. And again, I can "see" Mezzmo on the device, all my media (at least after a reset of the device), but then first time I access I get no sound, then second time I get the error message. I did a log submission a while back with this follow up:

In the log we can see two requests from the two direcTv boxes you have for the Mezzmo description document but no further request for Mezzmo icons or browsing of playlists so this indicates a communication block such as a firewall.