If Veeam Backup&Replication/Hyper-V and Veeam ONE are installed on the same server, try one of the following solutions in addition to the steps above:
Set-NetConnectionProfile -NetworkCategory Private
Or using the registry editor (machine restart will be required):
If changing the network type does not help, put Built-in Administrator account credentials for the Veeam Backup&Replication/Hyper-V server in the Connection Settings using the Veeam ONE Monitor Client.
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