FixTeamsFirewallMessage.ps1

<#
.SYNOPSIS
   Creates firewall rules for Teams.
.DESCRIPTION
   (c) Microsoft Corporation 2018. All rights reserved. Script provided as-is without any warranty of any kind. Use it freely at your own risks.
   Must be run with elevated permissions. Can be run as a GPO Computer Startup script, or as a Scheduled Task with elevated permissions. 
   The script will create a new inbound firewall rule for each user folder found in c:\users. 
   Requires PowerShell 3.0.
#>
#Requires -Version 3
$users = Get-ChildItem (Join-Path -Path $env:SystemDrive -ChildPath 'Users') -Exclude 'Public', 'ADMINI~*'
if ($null -ne $users) {
    foreach ($user in $users) {
        $progPath = Join-Path -Path $user.FullName -ChildPath "AppData\Local\Microsoft\Teams\Current\Teams.exe"
        if (Test-Path $progPath) {
            if (-not (Get-NetFirewallApplicationFilter -Program $progPath -ErrorAction SilentlyContinue)) {
                $ruleName = "Teams.exe for user $($user.Name)"
                "UDP", "TCP" | ForEach-Object { New-NetFirewallRule -DisplayName $ruleName -Direction Inbound -Profile Any -Program $progPath -Action Allow -Protocol $_ }
                Clear-Variable ruleName
            }
        }
        Clear-Variable progPath
    }
}