I was able to successfully connect a windows 2003 server to another by installing the Sonicwall global vpn client on one server and connecting to my TZ180 router. It assigns an IP correctly and allows traffic to pass. At first it was difficult to Drag and Drop files from a network share at \\ipaddress\sharename to the other servers desktop due to "zone warnings". I added the local IP of the remote server to the trusted zone of IE and that prompt went away. It appears that file access is normal because I can open files over the VPN or retrieve and copy them.
The problem is that I cannot sync an Access database over the vpn link. I could do this easily from my previous router. I have already tried "allow all traffic" firewall settings in the Sonicwall TZ180 for each public static IP and private static IP of each server machine. The database tries to replicate, but gets stuck after 1 progress bar unit and will not complete, claiming "disk or network error", like it is losing VPN connection or something. I can immediately go to Windows Explorer and can browse easily to the replication share location of the database. Anything with Sonicwalls that would prevent the replication?
I should also mention that I tried to use Windows based VPN and it had the same effect. I used RRAS in windows 2003 to connect the client server, and it used to work fine through my previous router. The RRAS still function sthrough the Sonicwall (enabling VPN pass-through) but the database syncronization is still blocked. Your help is much appreciated.