#Requires -Version 5.1
<#
    JbTecWiz Support Centre -- read-only diagnostic

    Fault : Remote Desktop: "an internal error has occurred" -- 0x204, 0x1104, 0x3
    Source: https://jbtecwiz.com/support/win-net-rdp-internal

    This script CHANGES NOTHING. It runs only the inspection commands
    from the write-up -- the Get-, Test- and Resolve- calls that
    establish which cause is in play -- and prints what each returned.
    Anything that writes, deletes, starts or stops is excluded by
    construction, not by judgement.

    Read the output alongside the write-up, then pick the fix that
    matches. Each fix has its own script on the same page.

    --------------------------------------------------------------------
    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([switch]$Transcript)
$ErrorActionPreference = 'Continue'

if ($Transcript) {
    $log = Join-Path $env:USERPROFILE ("jbtecwiz-win-net-rdp-internal-" + (Get-Date -Format yyyyMMdd-HHmmss) + ".txt")
    Start-Transcript -Path $log | Out-Null
    Write-Host ('  Saving a transcript to ' + $log)
}

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

function Probe { param([string]$Label, [string]$Fix, [scriptblock]$Command)
    Write-Rule ("  " + $Label)
    Write-Host ("  from: " + $Fix) -ForegroundColor DarkGray
    Write-Host ''
    foreach ($l in ($Command.ToString().Trim() -split "`n")) {
        Write-Host ("    " + $l.Trim()) -ForegroundColor DarkGreen
    }
    Write-Host ''
    try {
        $out = & $Command 2>&1 | Out-String
        if ([string]::IsNullOrWhiteSpace($out)) {
            Write-Host '    (returned nothing)' -ForegroundColor DarkGray
        } else {
            foreach ($l in ($out.TrimEnd() -split "`n")) { Write-Host ("    " + $l.TrimEnd()) }
        }
    } catch {
        Write-Host ("    could not run: " + $_.Exception.Message) -ForegroundColor Yellow
    }
}

Write-Rule
Write-Host '  Remote Desktop: "an internal error has occurred" -- 0x204, 0x1104, 0x3' -ForegroundColor White
Write-Host '  Read-only diagnostic -- nothing is changed.' -ForegroundColor Green
Write-Rule

Probe -Label 'Check what port it is on -- a previous change or a conflicting application moves it.' -Fix 'Confirm something is listening and reachable on 3389' -Command {
    Get-ItemProperty 'HKLM:\System\CurrentControlSet\Control\Terminal Server\WinStations\RDP-Tcp' -Name PortNumber
    Get-NetTCPConnection -State Listen -LocalPort 3389
}

Probe -Label 'Verify: The port answers from the client machine.' -Fix 'Confirm something is listening and reachable on 3389' -Command {
    Test-NetConnection target -Port 3389 -InformationLevel Detailed
}

Probe -Label 'Identify which end is unpatched. The correct fix is always to patch the server, not to weaken the client.' -Fix 'Resolve the CredSSP encryption oracle mismatch at the right end' -Command {
    Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 10 HotFixID,InstalledOn
}

Write-Rule
Write-Host '  Diagnostic finished. Nothing was changed.' -ForegroundColor Green
Write-Host ''
Write-Host '  Compare the output above with the write-up, then run the'
Write-Host '  script for the fix that matches:'
Write-Host '    https://jbtecwiz.com/support/win-net-rdp-internal'
Write-Rule
if ($Transcript) { Stop-Transcript | Out-Null }