(VB.NET) Check Internet Connectivity

Demonstrates an efficient way to test for Internet connectivity.

Chilkat .NET Downloads Chilkat .NET Framework Chilkat for .NET Core

Dim success As Boolean = False

Dim socket As New Chilkat.Socket
' 1. Use a reliable Anycast IP. 
'    8.8.8.8 (Google) or 1.1.1.1 (Cloudflare) are the industry standards.
Dim targetIp As String = "8.8.8.8"

' 2. Use Port 53 (DNS). 
'    DNS servers typically listen on TCP Port 53 as well as UDP. 
'    (Alternatively, use port 443 if you suspect port 53 is blocked).
Dim port As Integer = 53

' 3. Disable SSL (0). 
'    We are not doing a handshake, just a TCP connection.
Dim ssl As Boolean = False

' 4. Short Timeout (1500ms).
'    If you can't reach Google in 1.5 seconds, the connection is 
'    likely too poor for practical use anyway.
Dim timeoutMs As Integer = 1500

' Connect
success = socket.Connect(targetIp,port,ssl,timeoutMs)
If (success = False) Then
    Debug.WriteLine(socket.LastErrorText)
    Exit Sub
End If


socket.Close(10)

Debug.WriteLine("We have Internet connectivity.")