Windows Form integrated with Sql Server Connection Error

HI guys i have created a windows form application in visual studio 2012. In the load of the form i load a couple of datatables. But everytime one of the clients machine tries to access the server it gives them this error: A connection was successfully established with the server, but then an error occurred during the pre-login handshake. (provider: SSL Provider, error: 0 - The wait operation timed out.) i did a little research and started writing in CMD "Netsh Winsock Reset" then the program will connect and work fine. But every time they restart the machine it will not connect to the sql server.

Here a example of my code:

    Public lector As SqlDataReader
    Public adapter As New SqlDataAdapter
    Public comando As New SqlCommand
    Public con As New SqlConnection(Data Source=Sqlserver;Initial Catalog=ROPDB;Persist Security Info=True;User ID=UserID;Password= **********)

Private Sub MainForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        Try
           
            dtpEffective.Value = Date.Today
            dtpExpiration.Value = dtpEffective.Value.AddYears(3)

            txtUsername.Text = My.Settings.Username

            lblstripFecha1.Text = Date.Today.ToLongDateString

            adapter = New SqlDataAdapter("Select * From Bank", con)
            Bancos.Clear()
            adapter.Fill(Bancos)
            adapter.Dispose()
            cmbBanks1.DataSource = Bancos
            cmbBanks1.DisplayMember = "Name"
            cmbBanks1.ValueMember = "CODE"
            cmbBanks1.Refresh()
            cmbBanks1.SelectedIndex = -1