How to Connect to a PDB from my local SQL Developer Client?

Summary:

I have a VCN connected on my on-premise network via VPN connection, and I want to connect my local SQL Developer to my pluggable database in OCI.

Content (required):

The PDB (and Oracle DB System) is in a private subnet, and I have all traffic permission needed in security lists.

The DB System is accessible trought my OCI compute instances, that is into a public subnet.

OCI compute instances can reaches my on-premise devices, and my on-premise devices can reaches OCI compute instances.

Only DB System isn't reached from my on-premise network. When ping, the host is unreachable, when try connect on SQL Developer, a timeout error occours.