I change my subnet from 255.255.255.0 to 255.255.254.0 to allow more IPs. My old range is 192.168.1.0 - 192.168.1.254.
The new range is 192.168.0.0 - 192.168.1.254. The 192.168.1.x computers with the new subnet mask can still access the internet through Microsoft Forefront. The 192.168.0.x computers can not access the internet.
I added 192.168.0.1 - 192.168.1.254 to the internal address range in forefront but still no access. I also changed the mask on the internal network card on Forefront