Server '&1' does not receive address data, assign internal router

What causes this issue?

Business partner data is important in this scenario. The router is,
however, configured in such a way that it cannot receive business
partner address data. Instead, it can access the data of the internal
router. The internal router is not assigned to the scenario.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

If the external router supports the receiving of address data, change
the settings in the maintenance transaction <DS:TRAN.SBCA>SAP Routing
Server Adinistration</>, or assign the internal router to the scenario
as well.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.