SAP PO- Unable to open SSL connection to host, Peer certificate rejected by ChainVerifier

Hello Experts,

We have SAP PO 7.5 AEX AS Java Only installed on a HEC environment as part of our enterprise network, currently we are facing an error when we run the initial configuration wizard for SAP PO.

All the steps apparently are completed succesfully but when we get to check the SLD configuration the XI Components are not totally registred (Adapter Engine, Intergration directory, Integration Repository) due to a Certificate Error that is being rejected when trying to registering them to the SLD.

The NWA log viewer shows an error while the configuration wizard is running and when we try to register this manually through the RWB and following SAP Notes.

Exception while pinging the SLD
Thrown:
com.sap.lcr.api.cimclient.CIMClientException: IO error: Unable to open SSL connection to host "xxx". Peer certificate rejected by ChainVerifier.
at com.sap.lcr.api.cimclient.HttpRequestSender.send(HttpRequestSender.java:371)

We already check that SSL is configured correctly in the AS Java and all certificates are in green status

We already check some other configurations including the AII properties but none give us a clue to know whats the reason for this error.

I appreciate your comments and help to get this issue solved.