Test-NetConnection -AsJob?

Is there any way I can utilize this piece of code with Test-NetConnection -ComputerName $_ -Port 5985 instead of Test-Connection -ComputerName $_ -Count 1 -AsJob ? I can't utilize -AsJob with the Test-NetConnection cmdlet. Are there any workarounds?

Here is my code:

$online = @()
$pc = Get-Content C:\servers.txt 
$pc | ForEach-Object { 
    Test-Connection -ComputerName $_ -Count 1 -AsJob 
} | Get-Job | Receive-Job -Wait | 
Select-Object @{Name='ComputerName';Expression={$_.Address}},@{Name='Reachable';Expression={
    if ($_.StatusCode -eq 0) { 
        $true 
    } else { 
        $false 
    }
}} | ForEach-Object {
    if ($_.Reachable -eq $true) {
        $online += $_.ComputerName
    }
}
$online | ft -AutoSize

servers.txt just basically has hostnames of all the machines on the network.

Solution

With vanilla Windows PowerShell 5.1 the best you can get is using a RunspacePool, the code is not easy to follow and for a good reason there are many modules available to handle multithreading in PowerShell. The most recommended one would be ThreadJob.
This answer offers a "copy-pastable" version of a function that can handle multithreading from pipeline similar to ForEach-Object -Parallel but compatible with Windows PowerShell 5.1.

$ProgressPreference = 'Ignore'
$maxThreads = 32 # How many jobs can run at the same time?

$pool = [runspacefactory]::CreateRunspacePool(1, $maxThreads,
    [initialsessionstate]::CreateDefault2(), $Host)

$pool.Open()

$jobs = [System.Collections.Generic.List[hashtable]]::new()

Get-Content C:\servers.txt | ForEach-Object {
    $instance = [powershell]::Create().AddScript({
        param($computer)

        [pscustomobject]@{
            Computer = $computer
            Port     = 5985
            PortOpen = Test-NetConnection $computer -Port 5985 -InformationLevel Quiet
        }
    }).AddParameters(@{ computer = $_ })

    $instance.RunspacePool = $pool

    $jobs.Add(@{
        Instance = $instance
        Async    = $instance.BeginInvoke()
    })
}

$result = while($jobs) {
    $job = $jobs[[System.Threading.WaitHandle]::WaitAny($jobs.Async.AsyncWaitHandle)]
    $job.Instance.EndInvoke($job.Async)
    $job.Instance.Dispose()
    $null = $jobs.Remove($job)
}

$pool.Dispose()

$result | Where-Object PortOpen # filter only for computers with this port open