If you are using individual PSEs for the server components, then you must exchange the servers' public-key certificates. Use the procedure below, which begins the exchange on the AS ABAP.
You can also begin the exchange on the partner's host.
More information: Exporting the AS ABAP's Public-Key Certificate
More information: Maintaining the Server's Certificate List Using SAPGENPSE
More information: Exporting the Server's Certificate Using SAPGENPSE
More information: Importing Public-Key Certificates on the AS ABAP
The application server has the information it needs to identify its communication partner using SNC.
Continue with the connection-specific configurations.