error while establishing connection with sql server

string server = "1.1.1.1,1433";
var stringBuilder = new SqlConnectionStringBuilder
                    {
                        UserID = "id",
                        Password = "pass",
                        MultipleActiveResultSets = true,
                        DataSource = server,
                        NetworkLibrary = "DBMSSOCN",
                        InitialCatalog = "iCatalog"
                    };


using (var con = new SqlConnection(stringBuilder.ToString()))
{
    try
    {
        con.Open();
        MessageBox.Show("Connected");
    }
    catch (Exception exception)
    {
        MessageBox.Show(exception.Message);
    }
}

var server = @"MSSQL01\SQLENTW";

string server = "1.1.1.1\SQLENTW,1433"; 
or 
string server = "1.1.1.1:1433";