Code to telnet to an Actiontec DSL Gateway and reboot it if there is no internet connection.
Create a new Windows Service and paste this code into Service1.vb

Public Class RebootActiontec

Protected Overrides Sub OnStart(ByVal args() As String)
    ' Add code here to start your service. This method should set things
    ' in motion so your service can do its work.
    clt = New System.Net.Sockets.TcpClient
    MyTimer = New System.Threading.Timer(AddressOf MyTimer_Elapsed, Nothing, 300000, 300000) '5 minutes
End Sub

Protected Overrides Sub OnStop()
    ' Add code here to perform any tear-down necessary to stop your service.
    MyTimer.Change(System.Threading.Timeout.Infinite, System.Threading.Timeout.Infinite)
    MyTimer.Dispose()
    clt = Nothing
    stm = Nothing
End Sub

Dim WithEvents MyTimer As System.Threading.Timer
Dim clt As System.Net.Sockets.TcpClient
Dim stm As System.Net.Sockets.NetworkStream

Private Function RebootActiontec() As String
    Dim resp As String
    Try
        clt = New System.Net.Sockets.TcpClient
        clt.Connect("192.168.0.1", 23)                        'This is the IP Address of your DSL Gateway.
        stm = clt.GetStream
        resp = GetActiontecResponse()
        Threading.Thread.Sleep(1000)
        resp &= SendToActiontec("AdminID")        'Enter your own Admin ID here
        Threading.Thread.Sleep(1000)
        resp &= SendToActiontec("AdminPwd")    'Enter your own Admin Password here
        Threading.Thread.Sleep(1000)
        resp &= SendToActiontec("cd sbin")
        Threading.Thread.Sleep(1000)
        resp &= SendToActiontec("reboot")
        Threading.Thread.Sleep(1000)
        stm.Close()
        clt.Close()
    Catch ex As Exception
        resp = ex.Message
    End Try
    Return resp
End Function

Private Function SendToActiontec(ByVal msg As String) As String
    ' Send message to Actiontec
    Dim sendBytes As Byte() = System.Text.Encoding.ASCII.GetBytes(msg & vbCr)
    stm.Write(sendBytes, 0, sendBytes.Length)
    Return GetActiontecResponse()
End Function

Private Function GetActiontecResponse() As String
    Dim trm() As Char = {ControlChars.NullChar}
    Dim bytes(clt.ReceiveBufferSize) As Byte
    stm.Read(bytes, 0, CInt(clt.ReceiveBufferSize))
    Dim returndata As String = System.Text.Encoding.ASCII.GetString(bytes)
    Return returndata.Trim(trm)
End Function

Private Sub MyTimer_Elapsed(ByVal state As Object)
    'The following line can use any Internet IP address.  I used the IP Address shown under
    '"Gateway:" on the Actiontec's "Current Status" Page.
    Dim ping As Boolean = My.Computer.Network.Ping("67.42.227.193")
    If ping = False Then
        EventLog.WriteEntry(RebootActiontec)
    End If
End Sub

End Class