Communication with System & is not defined

What causes this issue?

The non-SAP system identified by communication number &V1& is not
defined for communication with your system.
IF &[SWITCH]S4H_DOCU_ON_PREMISE& = 'X'.

How to fix this error?

If you are authorized to do so, you can create communication numbers for
non-SAP systems, make changes and display existing table entries in
<GL:Customizing>Customizing</> as necessary.
ENDIF.

Error message extract from SAP system. Copyright SAP SE.