The RPC server is unavailable : Error running SharePoint PowerShell cmdlet

While running SharePoint PowerShell cmdlet, I was facing this error,

New-SPWebApplication : An error occurred while getting information about the user sp_admin at server winsmarts.internal: The RPC server is unavailable At C:\SharedFolder\CreatingIntranetSiteStructure.ps1:40 char:21

+ New-SPWebApplication <<<<  -Name $AppName -Port $Port  -ApplicationPool $AppPool -ApplicationPoolAccount (Get-SPManagedAccount $UserAccount) -databaseserver $DBServer -databasename $DBName

+ CategoryInfo          : InvalidData: (Microsoft.Share...PWebApplication: SPCmdletNewSPWebApplication) [New-SPWebApplication], InvalidOperationException

The script is doing nothing else creating a new Web Application.

New-SPWebApplication -Name $AppName -Port $Port -ApplicationPool $AppPool -ApplicationPoolAccount (Get-SPManagedAccount $UserAccount) -databaseserver $DBServer -databasename $DBName

SharePoint Server and Database Server is running on the same box. After some investigation, it was found that my machine was connected to VPN, and after disconnecting VPN and doing a machine restart, script runs fine. More investigation is needed to find reason of this problem but this is a possible resolution of such issue.