3435567 - Enterprise Event Enablement - OAuth Connection test for channel fails with error code 411 / NIECONN_REFUSED(-10)

When configuring an Event Mesh scenario as per SAP Help Creating SM59 Destination for SAP Event Mesh Validation Instance and testing whether an access token can be received when using the report OA2C_GENERIC_ACCESS, the following message is raised: 

>> lcl_oa2c_app->EXECUTE_ATR
granttype Client Credentials configured.

HTTP failure, processing failed, invalid state, invalid timeout or others
oa2c_error
Client configuration error or network problems. See kernel traces.
HTTPC Method:                  RECEIVE
HTTPC Subrc:                       1
HTTPC Subrc Text:              http_communication_failure
HTTPC get_last_error code:       411
HTTPC get_last_error message:
Direct connect to host.authentication.eu10.hana.ondemand.com:443 failed: NIECONN_REFUSED(-10)

• ABAP platform release independent
• SAP NetWeaver release independent
• SAP S/4HANA release independent

NIECONN_REFUSED(-10), 411, OA2C_GENERIC_ACCESS, Event Mesh Validation Service, http_communication_failure, oa2c_error, proxy, 3128, .ondemand.com, event mesh, mesh, oauth , KBA , BC-SEC-LGN-OA2 , OAuth 2.0 for ABAP , OPU-XBE , Enterprise Event Enablement , Problem