To validate the connectivity to Hyper-V hosts using PowerShell and attempt to reconnect in case of disconnection, you can use the following script. This script will check the connectivity to the specified Hyper-V hosts, and if any host is found to be disconnected, it will attempt to reconnect and display the error message in case of a disconnection.

# Replace 'HyperVHost1', 'HyperVHost2', etc., with the actual names or IP addresses of your Hyper-V hosts.
$HyperVHosts = @('HyperVHost1', 'HyperVHost2', 'HyperVHost3')

# Function to test the connectivity to a Hyper-V host
function Test-HyperVHostConnection {
    param (
        [string]$Host
    )
    try {
        # Test the connectivity to the Hyper-V host
        $result = Test-Connection -ComputerName $Host -Count 1 -Quiet
        if ($result) {
            Write-Host "Connected to $Host."
        } else {
            Write-Host "Disconnected from $Host."
            $false
        }
    }
    catch {
        Write-Host "Error occurred while testing the connection to $Host: $_"
        $false
    }
}

# Function to reconnect to a Hyper-V host
function Reconnect-HyperVHost {
    param (
        [string]$Host
    )
    try {
        # Reconnect to the Hyper-V host
        Write-Host "Reconnecting to $Host..."
        Connect-VIServer -Server $Host -ErrorAction Stop
        Write-Host "Reconnected to $Host successfully."
        $true
    }
    catch {
        Write-Host "Error occurred while reconnecting to $Host: $_"
        $false
    }
}

# Main script
try {
    foreach ($host in $HyperVHosts) {
        if (!(Test-HyperVHostConnection -Host $host)) {
            # Attempt to reconnect if the host is disconnected
            if (Reconnect-HyperVHost -Host $host) {
                # Perform any additional operations needed after a successful reconnection.
                # For example, you could list VMs, get their status, etc.
                # Get-VM -VMHost $host
            }
        }
    }
}
catch {
    Write-Host "Script encountered an error: $_"
}

In this script, we first define an array $HyperVHosts with the names or IP addresses of the Hyper-V hosts you want to test. The script then contains two functions:

1. Test-HyperVHostConnection: This function tests the connectivity to a Hyper-V host using the Test-Connection cmdlet. If the test succeeds, it displays a message indicating that the host is connected. If the test fails, it displays a message indicating that the host is disconnected.
2. Reconnect-HyperVHost: This function attempts to reconnect to a disconnected Hyper-V host using the Connect-VIServer cmdlet from PowerCLI. If the reconnection is successful, it displays a message indicating that the host was reconnected.

The main script iterates through the list of Hyper-V hosts, tests their connectivity, and attempts to reconnect if disconnected. If any errors occur during the connectivity test or reconnection process, the script will display the error message.

Please ensure you have the appropriate permissions to connect and manage Hyper-V hosts, and also make sure you have PowerCLI installed and properly configured before running the script.