After you add servers with Kerberos authentication, the servers might not be found because they are not added correctly.
When you try to connect to a server, the server is not found in Kerberos database.
No valid credentials provided (Mechanism level: No valid credentials provided (Mechanism level: Server not found in Kerberos database (7)))
This error might be caused by several misconfigurations.
The PowerShell host is not part of a domain.
The host to realm mapping is not correct.
The Service Principal Name of the PowerShell host is not built correctly.
Kerberos authentication does not work when the destination is an IP address.
When you add a PowerShell host using the Kerberos authentication, enter a DNS or NetBIOS destination.