How to Configure Windows Sandbox Local Traefik HTTP3 via XML in Windows 11

Evaluating HTTP/3 and QUIC transport protocol performance across edge reverse proxies requires testing UDP port 443 listeners and ALPN h3 advertisement headers. Traefik supports native HTTP/3 routing over UDP. Windows Sandbox on Windows 11 provides a secure, disposable container for validating HTTP/3 QUIC handshakes safely without altering host machine network adapters or production firewall rules.

Why Test HTTP/3 in Windows Sandbox

Testing QUIC protocol handshakes directly on host workstations can conflict with existing UDP services or local VPN clients. Launching Traefik inside an isolated Windows Sandbox enables engineers to test UDP 443 listeners, Alt-Svc header injection, and connection migration without risking workstation stability.

Authoring the Windows Sandbox WSB XML

Save the following XML document as TraefikHTTP3Sandbox.wsb on your Windows 11 machine:

<Configuration>
  <VGpu>Default</VGpu>
  <Networking>Default</Networking>
  <MappedFolders>
    <MappedFolder>
      <HostFolder>C:\TraefikHTTP3Lab</HostFolder>
      <SandboxFolder>C:\TraefikHTTP3Lab</SandboxFolder>
      <ReadOnly>true</ReadOnly>
    </MappedFolder>
  </MappedFolders>
  <LogonCommand>
    <Command>powershell.exe -ExecutionPolicy Bypass -NoExit -File C:\TraefikHTTP3Lab\setup-h3.ps1</Command>
  </LogonCommand>
</Configuration>

PowerShell Deployment Bootstrapper

Save the bootstrapping script as C:TraefikHTTP3Labsetup-h3.ps1:

Write-Host "Setting up Traefik HTTP/3 QUIC Lab..." -ForegroundColor Cyan

$Dir = "C:Traefik"
New-Item -ItemType Directory -Force -Path $Dir | Out-Null

$ZipUrl = "https://github.com/traefik/traefik/releases/download/v3.0.0/traefik_v3.0.0_windows_amd64.zip"
Invoke-WebRequest -Uri $ZipUrl -OutFile "$Dir	raefik.zip"
Expand-Archive -Path "$Dir	raefik.zip" -DestinationPath $Dir -Force

$Config = @"
experimental:
  http3: true
entryPoints:
  websecure:
    address: ":443"
    http3: {}
tls:
  stores:
    default:
      defaultCertificate:
        certFile: "C:/Traefik/cert.crt"
        keyFile: "C:/Traefik/cert.key"
"@

Set-Content -Path "$Dir	raefik.yml" -Value $Config
Write-Host "Traefik Configured for HTTP/3 QUIC on UDP Port 443." -ForegroundColor Green

Verifying Alt-Svc Headers

Launch the sandbox configuration and run curl requests against https://localhost. Confirm that Traefik returns the Alt-Svc: h3=":443"; ma=2592000 header, signaling HTTP/3 readiness to supporting browsers. Closing the sandbox leaves no residual configuration files.