RRAS with multiple networks....AD RPC Errors

I've setup a couple of domains behind an RRAS NAT setup.  I'm having all sorts of RPC issues.  I'm thinking RRAS is at fault.

Design Basics:

Root Domain:  lab.local
Network: 192.168.1.0/24

Sub Domain:  us.lab.local
Network: 192.168.2.0/24

Sites and Services is configured.  I was able to contact lab.local to create the us.lab.local domain.  When I run DCDIAG and check replication and so on I get RPC errors 1722. 

The router as mentioned has a NIC configured for Internet Access and a private nic that acts as the gateway for the lab.  So the private NIC has 192.168.1.1 and 2.1 as IP's.  All firewalls are disabled at this point.

I keep reading but can't find an answer except to go to a single network and avoid the router.

David Jenkins