Of course you can setup a Network Monitoring Tool (NMS) such as Zabbix. An easier and faster way is to run the following PowerShell script:

$hosts += "IP or DynDNS Name of my Routers"
$fname = "results.csv"
while($true) {
    $date = Get-Date -format G
    $newtime = Get-Date -format t
    # if ( $newtime -gt $time ) {
    if ( $true ) {
        $time = $newtime
        if ($hosts -isnot [system.array]) {
            $hosts = Get-Content $hosts
        }
        $hosts | Foreach-Object { 
            $pinghost = $_
            $psObject = $null
            $psObject = New-Object psobject
            Add-Member -InputObject $psobject -MemberType NoteProperty -Name "Date" -Value $date
            Add-Member -InputObject $psobject -MemberType NoteProperty -Name "Host" -Value $pinghost
            $status = Test-Connection –count 1 $pinghost  -ErrorAction SilentlyContinue
            if ($status.statuscode -eq 0) {
                $psobject | Add-Member -MemberType NoteProperty -Name "IP" -Value $status.IPV4Address
                $psobject | Add-Member -MemberType NoteProperty -Name "ResponseTime" -Value $status.ResponseTime
                $psobject | Add-Member -MemberType NoteProperty -Name "State" -Value "up"
                $psObject | Export-Csv $fname -Encoding UTF8 -Delimiter ";" -Append -NoTypeInformation
                Write-Host  $psObject 
            } else {
                $status2 = Test-Connection –count 1 $pinghost -ErrorAction SilentlyContinue
                if ($status2.statuscode -eq 0) {
                    $psobject | Add-Member -MemberType NoteProperty -Name "IP" -Value $status2.IPV4Address
                    $psobject | Add-Member -MemberType NoteProperty -Name "ResponseTime" -Value $status2.ResponseTime
                    $psobject | Add-Member -MemberType NoteProperty -Name "State" -Value "up"
                    $psObject | Export-Csv $fname -Encoding UTF8 -Delimiter ";" -Append -NoTypeInformation
                    Write-Host $psobject  -ForegroundColor black -BackgroundColor green
                } else {
                    $psobject | Add-Member -MemberType NoteProperty -Name "IP" -Value ="n/a"
                    $psobject | Add-Member -MemberType NoteProperty -Name "ResponseTime" -Value "-100"
                    $psobject | Add-Member -MemberType NoteProperty -Name "State" -Value "down"
                    $psObject | Export-Csv $fname -Encoding UTF8 -Delimiter ";" -Append -NoTypeInformation
                    Write-Host $psobject -BackgroundColor Red
                }
            }
        }
    }
    Write-Host "wait another 5 seconds for for next check ..."
    Start-Sleep 5
}