# WAC server name.
$ServerName = 'srv1'

# Import the WAC module (present on the workstation with WAC).
# This may require remote Powershell
# Enter-PSSession -ComputerName $ServerName
Import-Module "$env:ProgramFiles\windows admin center\PowerShell\Modules\ExtensionTools"

# WAC address
$WAC = "https://$ServerName/"

# List installed extensions that do not have the latest version
$extensions = Get-Extension $WAC | Where-Object {($_.isLatestVersion -match "false") -and ($_.status -eq "installed") } | Select-Object -ExpandProperty id

# Update extensions
ForEach ($extension in $extensions)
{
    Update-Extension $WAC -ExtensionId $extension -Verbose
}