Connection test failed

What causes this issue?

The system could not establish a link to an optimization server.

System Response

Bevor an optimization server is started, the system tries to test the
RFC link. This test failed.

How to fix this error?

The optimization run cannot be started. Exit the transaction.

Procedure for System Administrators

Check the system status of the optimization server or SAP gateways.

Error message extract from SAP system. Copyright SAP SE.