The Auto Discovery function is limited to a single Active Directory domain. The DN (Distinguished Name) is reduced and does not contain any domain information.
Instead, the domain information is stored centrally in the Core & Probes area and thus applies to the entire environment.
For Auto Discovery, not only should the authorized user and OU be queried, but also the domain for this Auto Discovery. In large companies, multiple domains are often used and are not limited to individual subnets.