During the maintenance and updating of the Horizon Connection server components, one aspect is the necessary wait for the connection servers to correctly resume responding on TCP port 443.
During one of the many activities on Horizon my customer created a simple and effective door test script.
Even though it is very simple and intuitive, I want to share the code with you:

do {
    $check = netstat -ano | findstr 0.0.0.0:443
    "Waiting 5 seconds and retry" 
    sleep 5
} while (!$check)
$check