RDCMan是微软出品的一个十分方便的远程桌面连接工具。但是当连接到 Hyper-V 主机的时候有时会出现以下错误“Unknown disconnection reason 3848”如图所示

出错原因：

the Credential Security Service Provider (CredSSP) policy on the Hyper-V host is not enabled to authenticate user credentials from a remote location.

解决方法：

启动PowerShell，执行以下命令：

New-ItemProperty -Path HKLM:\SYSTEM\CurrentControlSet\Control\Lsa\Credssp\PolicyDefaults\AllowDefaultCredentials -Name Hyper-V -PropertyType String -Value "Microsoft Virtual Console Service/*" -Force
New-ItemProperty -Path HKLM:\SYSTEM\CurrentControlSet\Control\Lsa\Credssp\PolicyDefaults\AllowDefaultCredentialsDomain -Name Hyper-V -PropertyType String -Value "Microsoft Virtual Console Service/*" -Force
New-ItemProperty -Path HKLM:\SYSTEM\CurrentControlSet\Control\Lsa\Credssp\PolicyDefaults\AllowFreshCredentials -Name Hyper-V -PropertyType String -Value "Microsoft Virtual Console Service/*" -Force
New-ItemProperty -Path HKLM:\SYSTEM\CurrentControlSet\Control\Lsa\Credssp\PolicyDefaults\AllowFreshCredentialsDomain -Name Hyper-V -PropertyType String -Value "Microsoft Virtual Console Service/*" -Force
New-ItemProperty -Path HKLM:\SYSTEM\CurrentControlSet\Control\Lsa\Credssp\PolicyDefaults\AllowFreshCredentialsWhenNTLMOnly -Name Hyper-V -PropertyType String -Value "Microsoft Virtual Console Service/*" -Force
New-ItemProperty -Path HKLM:\SYSTEM\CurrentControlSet\Control\Lsa\Credssp\PolicyDefaults\AllowFreshCredentialsWhenNTLMOnlyDomain -Name Hyper-V -PropertyType String -Value "Microsoft Virtual Console Service/*" -Force
New-ItemProperty -Path HKLM:\SYSTEM\CurrentControlSet\Control\Lsa\Credssp\PolicyDefaults\AllowSavedCredentials -Name Hyper-V -PropertyType String -Value "Microsoft Virtual Console Service/*" -Force
New-ItemProperty -Path HKLM:\SYSTEM\CurrentControlSet\Control\Lsa\Credssp\PolicyDefaults\AllowSavedCredentialsDomain -Name Hyper-V -PropertyType String -Value "Microsoft Virtual Console Service/*" -Force
New-ItemProperty -Path HKLM:\SYSTEM\CurrentControlSet\Control\Lsa\Credssp\PolicyDefaults\AllowSavedCredentialsWhenNTLMOnly -Name Hyper-V -PropertyType String -Value "Microsoft Virtual Console Service/*" -Force

参考资料：

• When I use the Virtual Machine Connection tool to connect to a virtual machine on a Windows Server 2008 Hyper-V-based computer I receive an error message: "A connection will not be made because credentials may not be sent to the remote computer"

• RDCMan v2.7 Unknown disconnection reason 3848