Building a forefront Thread Management Gateway security firewall

I am building a forefront Thread Management Gateway security firewall (TMG). My internet has a Network internet controller (NIC) connected to a LAN then to a modem and a switch. I am trying to do PoPE cabling which is working pretty good but the problem is that it is not supporting the (TMG). I have tried to create another dial up connection but it’s still not working and the internet traffic indicates that the TTL has expired, seems like it cannot ping. I even tried to disable the bridge mode in the router but still there is no internet access. Does anyone have a suggestion on how to make this work?
