Cannot access FQDN over site-to-site VPN tunnel

Hello,

Site A – PDC/DNS/GC/File Shares
Site B – DNS/GC

From either site the DNS servers can access each other by either IP or FQDN. From either site, User PCs CAN access the remote server by IP but NOT FQDN. Each site is in a different subnet.

This is causing issues with login scripts, etc.

Ports 445, 135, 139 are open between the sites.

Any help is greatly appreciated in this matter!

Thanks.