Use cases of Private Link for Azure Database for PostgreSQL

Clients can connect to the private endpoint from the same VNet, peered VNet in same region or across regions, or via VNet-to-VNet connection across regions. Additionally, clients can connect from on-premises using ExpressRoute, private peering, or VPN tunneling. Below is a simplified diagram showing the common use cases.

Source: Private Link - Azure Database for PostgreSQL - Single server | Microsoft Docs