Probably used a different IP range to your old network, so your firewall didn't recognise it as being a LAN. That's just an assumption though, I can't think of anything else without further information sorry.
I Think You are using a different types of IP set (Internet Protocol) along with your wireless network.So That There will be problem with a Connection with Your Wireless LAN.So That You Have To Disable Your Firewall.
You didn't give us lot of information. I guess you have taken AT&T U-verse service.
This U-verse service has its own firewall. It is not wise to have two firewalls in one home network, they can end up in disabling the traffic which is important.
Wireless home security network 
Linear Mode
