You need to make your local network a trusted zone.
How to make your local network a trusted zone.?
First look up your IP address and subnet mask. In Windows go to Start --> Run --> cmd --> enter --> ipconfig --> enter --> now lookup your IP address and subnet mask.
Second create a zone in My Network Zones (Firewall --> Network Security policy). Choose Add --> A New Network Zone --> fill in a name like My local network --> Apply. Now select My Local Network Zone --> Add --> A new address --> choose An IP Address Mask --> fill in your local IP something like 192.168.1.x usually and your subnet mask; usually 255.255.255.0 --> Apply. Now check and see the new network defined. Exit using Apply.
Now we are going to use the Stealth Ports Wizard to make your local network a trusted network:
Choose "Define a new trusted network and stealth my ports to EVERYONE else" --> Next --> choose "I would like to trust an existing My Network Zone" --> choose your local network zone from the drop down box at the bottom --> Finish.
Now check your Global Rules and see your network added.
I did all that and WMC still cannot detect the Xbox as the extender. Here's the suggestion I'm getting from Xbox but I have no idea how to find or add the port number(1900).
Error: "Cannot detect Extender"
This usually means that a firewall on your computer is blocking the Extender. If you have more than one firewall installed, check the error message to see if it specifies which firewall is blocking your Extender, or see Determine which firewalls are installed on your computer later in this article.
Then try the following:
Open the firewall on your computer. In the firewall settings, open the following exception:
Program Service Local port Remote port Direction Network Needed for
svchost.exe ssdpsrv UDP 1900 Random Inbound Local subnet Device discovery