Dns problem

we have simple problem we connecting two branch with apeplink using site to site vpn but when we try to bing by name from pc in branch to pc in another branch cant reach we find that they cant resolve pc name with dns in active directory in main branch so cant communicate with database server

Pc names can unfortunately not be used over a VPN. If you, for example, have more than one Pc with the same name, but at two different sites, how will the router know which one you want to communicate with? There is luckily a solution to the problem. On the LAN configuration page of your Peplink, you can configure local DNS records, associating a device name to a unique IP adress. Create such an entry that points your database server’s name to the server’s IP adress, and your problem should be resolved.