ADG configuration failing in ExaCS

Summary:

In ExaCS environment , when we enable Dataguard between CDB database from primary region to Secondary region it is failing with error reported "Listener port is not reachable on local or remote nodes" - But when we verified listener ports are open and connectivity is working fine between primary and standby regions.

what is causing this issue ?

Content (required):

dg_api:CDG-50107 : DataGuard prechecks failed for stage VERIFY_DG_STANDBY

Version (include the version you are using, if applicable):

ExaCS X9M-2 , database version 19.14

Code Snippet (add any code snippets that support your topic, if applicable):

dg_api:CDG-50107 : DataGuard prechecks failed for stage VERIFY_DG_STANDBY