If the error listed on this KB article occurs while using the built-in Administrator account or a domain account that is a member of the local Administrators group, the issue may be related to a firewall or NAT. During the initial connection to the Hyper-V server, Veeam Backup & Replication will attempt to communicate with the Hyper-V server to determine if it is, in fact, a Hyper-V server. If those connections fail, the error on this KB will occur. Review the Used Ports
section of the User Guide.