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

    Fault : "The specified network name is no longer available"
    Fix   : Raise the file server's SMB resource limits
    Source: https://jbtecwiz.com/support/srv-smb-network-name

    Run as     : Elevated PowerShell on the file server
    Expect     : 40 minutes
    Risk       : medium
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    Several clients are affected by one server. Event 2017 confirms it.

    HOW TO UNDO IT
    Set Size back to its previous value and MaxThreadsPerQueue to 20.

    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 6"
    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 '  Raise the file server''s SMB resource limits' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: medium   Reversible   40 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 'Look for the resource exhaustion event.' -Command {
    Get-WinEvent -FilterHashtable @{LogName='System'; Id=2017} -MaxEvents 10 -ErrorAction SilentlyContinue | Format-List TimeCreated, Message
}

Invoke-Step -Number 2 -Do 'Check the current SMB server configuration.' -Command {
    Get-SmbServerConfiguration | Format-List MaxChannelPerSession, MaxSessionPerConnection, MaxThreadsPerQueue, AsynchronousCredits
}

Invoke-Step -Number 3 -Do 'Raise the memory the SMB server may use for large requests.' -Why 'Size=3 tunes the server for file sharing over other roles. It is the documented first move for 2017 and needs a restart.' -Command {
    Set-ItemProperty 'HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters' -Name 'Size' -Value 3 -Type DWord
}

Invoke-Step -Number 4 -Do 'Raise the worker threads if the server has many concurrent clients.' -Command {
    Set-SmbServerConfiguration -MaxThreadsPerQueue 60 -Force
}

Invoke-Step -Number 5 -Do 'Check the NIC''s receive-side scaling is on so SMB traffic is spread across cores.' -Command {
    Get-NetAdapterRss | Format-Table Name, Enabled, NumberOfReceiveQueues -AutoSize
}

Invoke-Step -Number 6 -Do 'Restart the server at a scheduled time -- most of these settings need it.' -Manual

Write-Rule "  Confirm it worked"
Show-Prose 'No further 2017 events and copies complete.' 'White'
Write-Host ''
if (-not $DryRun) {
    Get-SmbServerConfiguration | Format-List MaxThreadsPerQueue
    Get-Counter '\Server\Work Item Shortages' -SampleInterval 5 -MaxSamples 3
}

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: Set Size back to its previous value and MaxThreadsPerQueue to 20.' 'DarkGray'
Write-Rule