More about FIREWALLs. EXAMPLE.
Your router's firewall can block many features. You have a choice here to turn it off or dig in and find out what ports and more to allow. Given the cost of support and the fact that routers in the past never did this, my vote for those that don't want to become Network Ninja Gurus is to turn it off.
With that out of the way, an example from a router I recently discussed.
See Page 43: http://www.downloads.netgear.com/files/GDC/DGN2200/DGN2200_UM_3Feb11.pdf
"Your modem router has a firewall that blocks unauthorized access to your wireless network and permits authorized inbound and outbound communications. Authorized communications are established according to inbound and outbound rules. The firewall has the following two default rules. You can create custom rules to further restrict the outbound communications or more widely open the inbound communications:
• Inbound. Block all access from outside except responses to requests from the LAN side.
• Outbound. Allow all access from the LAN side to the outside"
Notice how an inbound access from WiFi is blocked? You'll want to change that.
Page 44 (using the page counter in the PDF viewer) shows the default is BLOCK ALWAYS.
This means features like access to a DLNA, NAS or other server can fail.
You'll want to temper your flames to the TV makers on this area. They didn't setup your router and in most cases, it's not their product.