If you need to find out how many concurrent user connections on to your WFE, you need to use the below script.  THe script uses Win32_PerfFormattedData_W3SVC_WebService performance Counter to give you exactly how many people are hitting a WFE and will send an email.  I have created a scheduled task that runs every hour from 9 ET to 4 ET.  

Add-PSSnapin "Microsoft.SharePoint.PowerShell" -ErrorAction SilentlyContinue
#The mail address of who will receive the backup exception message
$from = “spadmin@contoso.com”
#Send email function
function SendMail($subject, $body)
{
    try
    {
        #Getting SMTP server name and Outbound mail sender address
        $caWebApp = (Get-SPWebApplication -IncludeCentralAdministration) | ? { $_.IsAdministrationWebApplication -eq $true }
        $smtpServer = $caWebApp.OutboundMailServiceInstance.Server.Address
        $smtp = new-object Net.Mail.SmtpClient($smtpServer)

        #Creating a Mail object
        $message = New-Object System.Net.Mail.MailMessage
        $message.Subject = $subject
        $message.Body = $body
        $To = someone@contoso.com
        $message.To.Add($To1)
        $message.From = $from
             
        #Creating SMTP server object
        
    
        #Sending email
        $smtp.Send($message)
        Write-Host "Email has been Sent!"
    }
    catch [System.Exception]
    {
        Write-Host "Mail Sending Error:" $_.Exception.Message -ForegroundColor Red
    }
}

$String = ""
$String +="==============================================================================`n"
$String +="                 !!!!!    Connections Alert     !!!!!  `n"
$String +="==============================================================================`n"

#Change the value as per need
[system.int32]$Threshold = 100
[System.Boolean]$EmailNeed = $false
Write-Host "Server      : Connections"
Write-Host "============================"
$String +="Server            :     Connections Count`n"
$String +="==============================================================================`n"
$ServerCSV = ""

Get-WmiObject -Class Win32_PerfFormattedData_W3SVC_WebService -ComputerName Server1,Server2,Server3,Server4 | Where {$_.Name -eq "_Total"} | % `
{
    $ServerName = $_.__SERVER;
    $Connections = $_.CurrentConnections
    $String +="$ServerName : $Connections`n"
    Write-Host "$ServerName : $Connections" 
}

$String +="`n`n==============================================================================`n"
$String +="This is just an alert.  Please contact someone@contoso.com for more information.`n"

$Date = Get-Date
SendMail -subject "SharePoint : ! Connections !: Time: $Date" -body $String

Write-Host "Done.."

#Examples of how to find the required Counters
#Get-WmiObject -List | ? Name -like "*NetLogon*"
#Get-WmiObject -List | ? Name -like "*NetLogon*" | Select Name
#Get-WmiObject -List | ? Name -like "*NetLogon*" | Select -ExpandProperty Properties
#Get-WmiObject -Class Win32_PerfFormattedData_Counters_Netlogon -ComputerName Server1,Server2,Server3,Server4 | Where {$_.Name -eq "_Total"} | % {Write-Host $_.__SERVER;Write-Host $_.SemaphoreTimeouts}

Save the above script as GetConnect-FromServes.ps1

Scheduled Task XML

<?xml version="1.0" encoding="UTF-16"?>
<Task version="1.2" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task">
  <RegistrationInfo>
    <Date>2015-08-20T15:54:47.5695947</Date>
    <Author>Domain\UserName</Author>
  </RegistrationInfo>
  <Triggers>
    <CalendarTrigger>
      <Repetition>
        <Interval>PT5M</Interval>
        <Duration>P1D</Duration>
        <StopAtDurationEnd>false</StopAtDurationEnd>
      </Repetition>
      <StartBoundary>2015-08-20T15:52:04.6019445</StartBoundary>
      <Enabled>true</Enabled>
      <ScheduleByDay>
        <DaysInterval>1</DaysInterval>
      </ScheduleByDay>
    </CalendarTrigger>
  </Triggers>
  <Principals>
    <Principal id="Author">
      <UserId>Domain\UserName</UserId>
      <LogonType>Password</LogonType>
      <RunLevel>LeastPrivilege</RunLevel>
    </Principal>
  </Principals>
  <Settings>
    <MultipleInstancesPolicy>IgnoreNew</MultipleInstancesPolicy>
    <DisallowStartIfOnBatteries>true</DisallowStartIfOnBatteries>
    <StopIfGoingOnBatteries>true</StopIfGoingOnBatteries>
    <AllowHardTerminate>true</AllowHardTerminate>
    <StartWhenAvailable>false</StartWhenAvailable>
    <RunOnlyIfNetworkAvailable>false</RunOnlyIfNetworkAvailable>
    <IdleSettings>
      <StopOnIdleEnd>true</StopOnIdleEnd>
      <RestartOnIdle>false</RestartOnIdle>
    </IdleSettings>
    <AllowStartOnDemand>true</AllowStartOnDemand>
    <Enabled>true</Enabled>
    <Hidden>false</Hidden>
    <RunOnlyIfIdle>false</RunOnlyIfIdle>
    <WakeToRun>false</WakeToRun>
    <ExecutionTimeLimit>P3D</ExecutionTimeLimit>
    <Priority>7</Priority>
  </Settings>
  <Actions Context="Author">
    <Exec>
      <Command>C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe</Command>
      <Arguments>-ExecutionPolicy Bypass E:\Scripts\GetConnect-FromServes.ps1</Arguments>
    </Exec>
  </Actions>
</Task>

Save the above XML as File and Open the Task in Task Schedule.  Change Credentials and Script Locations.