You might want to take a look at Microsoft Knowledge Base Article # 816581. Here’s the link.
According to this article, the DNS entry on the internal NIC should be the DNS IP address provided by your ISP. Also, you need to have routing enabled on the server TCP/IP properties.
But it’s not clear to me why you have two different internal subnets. Is there a reason not to put everyone in 10.x, or in 192.168.x? That would simplify the setup.
I posted the following 8/22… the wiki takes a little getting used to….
Can they not get to the internet or can they not resolve? Do you have dns forwarding set up? try browsing to an ip address.also, check routes