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

    Fault : "The specified network name is no longer available"
    Fix   : Rule out offloading and idle timeouts on the client path
    Source: https://jbtecwiz.com/support/srv-smb-network-name

    Run as     : Elevated PowerShell on the client
    Expect     : 30 minutes
    Risk       : low
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    One machine is affected.

    HOW TO UNDO IT
    Re-enable the offload settings as in step 4.

    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 '  "The specified network name is no longer available"' -ForegroundColor White
Write-Host '  Rule out offloading and idle timeouts on the client path' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: low   Reversible   30 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 'Test the path holds up under a sustained transfer.' -Command {
    Test-NetConnection -ComputerName FS01 -Port 445 -InformationLevel Detailed
}

Invoke-Step -Number 2 -Do 'Turn off the offload features that most often corrupt or drop long SMB transfers.' -Why 'This is a diagnostic step, not a permanent configuration -- offload exists for good reason. If disabling it fixes the problem, the answer is a NIC driver update, not leaving it off.' -Command {
    Disable-NetAdapterLso -Name '*'
    Set-NetOffloadGlobalSetting -Chimney Disabled
    Set-NetOffloadGlobalSetting -TaskOffload Disabled
}

Invoke-Step -Number 3 -Do 'Stop the session being closed while idle.' -Command {
    Set-SmbClientConfiguration -SessionTimeout 300 -Force
}

Invoke-Step -Number 4 -Do 'Update the network driver from the machine vendor and re-enable offloading.' -Command {
    Enable-NetAdapterLso -Name '*'
    Set-NetOffloadGlobalSetting -TaskOffload Enabled
}

Invoke-Step -Number 5 -Do 'Check for a firewall or IPS between the two dropping long-lived sessions.' -Manual

Write-Rule "  Confirm it worked"
Show-Prose 'A large file copies end to end without failing.' 'White'

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-smb-network-name' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: Re-enable the offload settings as in step 4.' 'DarkGray'
Write-Rule