#Requires -Version 5.1
<#
    JbTecWiz Support Centre -- generated fix script

    Fault : Virtual machines lose network after a host change
    Fix   : Restore the switch's uplink
    Source: https://jbtecwiz.com/support/srv-clu-vm-network

    Run as     : Elevated PowerShell on the host
    Expect     : 45 minutes
    Risk       : medium
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    Everything on one host has lost connectivity.

    HOW TO UNDO IT
    Remove-VMSwitchTeamMember reverses an added member.

    This script walks the fix one step at a time and asks before each
    one. Steps with no command are things you do yourself -- it prints
    those and waits. Run with -DryRun to print without executing.

    --------------------------------------------------------------------
    NO WARRANTY - USE AT YOUR OWN RISK

    This script is provided by JbTecWiz as-is and with no warranty of any
    kind, express or implied. You run it entirely at your own risk.

    JbTecWiz accepts no liability for any loss or damage arising from its
    use, including but not limited to data loss, downtime, or configuration
    changes that turn out to be wrong for your system.

    You are responsible for reading this script before running it, for
    satisfying yourself that it suits the machine in front of you, and for
    having a working backup first. Some steps cannot be undone.
    --------------------------------------------------------------------
#>

[CmdletBinding()]
param(
    # Print every step and command without running anything.
    [switch]$DryRun,
    # Do not ask before each step. Read the script first if you use this.
    [switch]$Unattended
)

$ErrorActionPreference = 'Stop'
$script:Failed = 0

function Write-Rule { param([string]$Text)
    Write-Host ''
    Write-Host ('-' * 70) -ForegroundColor DarkGray
    if ($Text) { Write-Host $Text -ForegroundColor Cyan }
}

function Show-Prose { param([string]$Text, [string]$Colour = "Gray")
    if (-not $Text) { return }
    $words = $Text -split "\s+"; $line = "  "
    foreach ($w in $words) {
        if (($line.Length + $w.Length) -gt 74) { Write-Host $line -ForegroundColor $Colour; $line = "  " }
        $line += "$w "
    }
    if ($line.Trim()) { Write-Host $line -ForegroundColor $Colour }
}

function Invoke-Step {
    param(
        [int]$Number, [string]$Do, [string]$Why,
        [scriptblock]$Command, [switch]$Manual, [string]$Shell = "powershell"
    )
    Write-Rule "  Step $Number of 5"
    Show-Prose $Do "White"
    if ($Why) { Write-Host ""; Show-Prose $Why "DarkGray" }

    if ($Manual) {
        Write-Host ''
        Write-Host '  -> Do this yourself, then press Enter to carry on.' -ForegroundColor Yellow
        if (-not $Unattended -and -not $DryRun) { [void](Read-Host) }
        return
    }

    Write-Host ''
    foreach ($l in ($Command.ToString().Trim() -split "`n")) {
        Write-Host ("    " + $l.Trim()) -ForegroundColor Green
    }
    Write-Host ''

    if ($DryRun) { Write-Host "  (dry run -- not executed)" -ForegroundColor DarkGray; return }
    if (-not $Unattended) {
        $a = Read-Host "  Run this step? [Y]es / [S]kip / [Q]uit"
        if ($a -match "^[Qq]") { Write-Host "  Stopped at your request."; exit 0 }
        if ($a -match "^[Ss]") { Write-Host "  Skipped." -ForegroundColor DarkGray; return }
    }
    try { & $Command }
    catch {
        $script:Failed++
        Write-Host ("  Step $Number failed: " + $_.Exception.Message) -ForegroundColor Red
        Show-Prose "The rest of the fix may depend on this. Read the write-up before carrying on." "Red"
        if (-not $Unattended) {
            $c = Read-Host "  Carry on anyway? [y/N]"
            if ($c -notmatch "^[Yy]") { exit 1 }
        }
    }
}

Write-Rule
Write-Host '  Virtual machines lose network after a host change' -ForegroundColor White
Write-Host '  Restore the switch''s uplink' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: medium   Reversible   45 minutes'
Write-Host ''
Show-Prose 'No warranty. Use at your own risk - JbTecWiz accepts no liability. Read it before you run it, and have a backup.' 'DarkYellow'
Write-Rule

if (-not $Unattended -and -not $DryRun) {
    $go = Read-Host '  Ready? [y/N]'
    if ($go -notmatch "^[Yy]") { Write-Host "  Nothing was changed."; exit 0 }
}

Invoke-Step -Number 1 -Do 'Check the switch and its team members.' -Command {
    Get-VMSwitch | Format-List Name,SwitchType,NetAdapterInterfaceDescription,EmbeddedTeamingEnabled
    Get-VMSwitchTeam | Format-List Name,NetAdapterInterfaceDescription,TeamingMode,LoadBalancingAlgorithm
}

Invoke-Step -Number 2 -Do 'Check each physical member is up.' -Why 'A SET team with one member down keeps working and gives no obvious sign. With the last member down the switch stays present and every virtual machine loses its network, which reads as a Hyper-V fault rather than a cable.' -Command {
    Get-NetAdapter | Format-Table Name,Status,LinkSpeed,InterfaceDescription
    Get-VMSwitchTeam | Select-Object -ExpandProperty NetAdapterInterfaceDescription
}

Invoke-Step -Number 3 -Do 'Re-add a member that has dropped out.' -Command {
    Add-VMSwitchTeamMember -VMSwitchName 'vSwitch-Prod' -NetAdapterName 'Ethernet 2'
}

Invoke-Step -Number 4 -Do 'Check the management operating system''s own adapter on that switch if the host itself has also lost connectivity.' -Command {
    Get-VMNetworkAdapter -ManagementOS | Format-Table Name,SwitchName,MacAddress,Status
    Get-NetIPConfiguration -Detailed | Format-List InterfaceAlias,IPv4Address,IPv4DefaultGateway
}

Invoke-Step -Number 5 -Do 'Verify the physical switch ports are configured identically for every member of the team -- a mismatch produces intermittent loss rather than a clean failure.' -Manual

Write-Rule "  Confirm it worked"
Show-Prose 'Virtual machines have connectivity and every team member is up.' 'White'
Write-Host ''
if (-not $DryRun) {
    Get-VMSwitchTeam | Format-List Name,NetAdapterInterfaceDescription
    Get-VM | Get-VMNetworkAdapter | Format-Table VMName,Status,IPAddresses
}

Write-Rule
if ($script:Failed -gt 0) {
    Write-Host ("  Finished with " + $script:Failed + " failed step(s).") -ForegroundColor Yellow
    Show-Prose 'Read the full write-up at https://jbtecwiz.com/support/srv-clu-vm-network' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: Remove-VMSwitchTeamMember reverses an added member.' 'DarkGray'
Write-Rule