Unable to connect to the Oracle WSM Policy Manager

on a OSB domain with OWSM installed, we had this error when editing the policies associated to a WSDL-based service:

oracle.wsm.policymanager.PolicyManagerException: WSM-02120 : Unable to connect to the Oracle WSM Policy Manager due to the following error "javax.naming.CommunicationException [Root exception is java.net.ConnectException: t3s://acme.com:8002: Destination unreachable; nested exception is:
javax.net.ssl.SSLKeyException: [Security:090477]Certificate chain received from hqchnesoa102.acme.com - 10.53.5.192 was not trusted causing SSL handshake failure.; No available router to destination]". [Possible Cause : Destination unreachable; nested exception is:
javax.net.ssl.SSLKeyException: [Security:090477]Certificate chain received from hqchnesoa102.acme.com - 10.53.5.192 was not trusted causing SSL handshake failure.; No available router to destination]

The root cause was that the Admin server was using a Demo Identity and trust store, while the Managed Servers were using a Custom one. Setting the Admin the same way as the Managed fixed the issue.