It says “By default, this command is not available. It is only available as a factory
(SKU-level) configuration.”
Have you tried to enter as the example?
AT!PARTITION=0:LEFWKRO,16000
You can also check if the command is already “disable”, if it is disabled, you cannot have partition change:
Query List: ATPARTITION=?
Purpose: Return the execution command format and the supported parameter values.
If !PARTITION is not enabled, the response will include “None/Not Allowed”
instead of a list of partitions.