Test if port is open on multiple IP Quickly ( List of Server )

Hello, i have a list of server and 2 server running. i display the server well the user can choose wich one they want. now i have try to integrate a script for test port on a ip. i have tryed like this :

UdpClient UdpScan = new UdpClient();

try{ UdpScan.Connect("127.0.0.1", 5055); Server1Open = true; } catch { Server1Open = false; } finally { UdpScan.Close; }

but this not worked. the Server1Up is always true.

Anyone know a method to use to test if server is up. the scripts need to be really quick. The list of server is displayed on the load of the scene. if you have another idea for test if my server is up share me it. Thanks for your help