I'm looking for code that would help me check the user's internet connection. For example, when Button1 is clicked a MsgBox appears that displays either "Connected" or "Disconnected" based on whether they are connected to the internet or not.

Here.. try this..

Private Declare Function InternetGetConnectedStateEx Lib "wininet.dll" (ByRef lpdwFlags As Long, ByVal lpszConnectionName As String, ByVal dwNameLen As Integer, ByVal dwReserved As Long) As Long

Dim sConnType As String * 255

Sub CheckNetCon()
Dim Ret As Long
Ret = InternetGetConnectedStateEx(Ret, sConnType, 254, 0)
If Ret = 1 Then
    MsgBox "You are connected to Internet via a " & sConnType, vbInformation
Else
    MsgBox "You are not connected to internet", vbInformation
End If

End Sub

Reference: http://www.ex-designz.net/apidetail.asp?api_id=465

you can use followig code to check internet connection at form
Private Declare Function InternetGetConnectedState Lib "wininet" _
(ByRef dwFlags As Long, _
ByVal dwReserved As Long) As Long

'Local system uses a modem to connect to the Internet.
Private Const INTERNET_CONNECTION_MODEM As Long = &H1

'Local system uses a LAN to connect to the Internet.
Private Const INTERNET_CONNECTION_LAN As Long = &H2

'Local system uses a proxy server to connect to the Internet.
Private Const INTERNET_CONNECTION_PROXY As Long = &H4

'No longer used.
Private Const INTERNET_CONNECTION_MODEM_BUSY As Long = &H8

Private Const INTERNET_RAS_INSTALLED As Long = &H10
Private Const INTERNET_CONNECTION_OFFLINE As Long = &H20
Private Const INTERNET_CONNECTION_CONFIGURED As Long = &H40


Private Sub Command1_Click()

Text1.Text = IsNetConnectViaLAN()
Text2.Text = IsNetConnectViaModem()
Text3.Text = IsNetConnectViaProxy()
Text4.Text = IsNetConnectOnline()
Text5.Text = IsNetRASInstalled()
Text6.Text = GetNetConnectString()

End Sub


Private Function IsNetConnectViaLAN() As Boolean

Dim dwflags As Long

'pass an empty variable into which the API will
'return the flags associated with the connection
Call InternetGetConnectedState(dwflags, 0&)

'return True if the flags indicate a LAN connection
IsNetConnectViaLAN = dwflags And INTERNET_CONNECTION_LAN

End Function


Private Function IsNetConnectViaModem() As Boolean

Dim dwflags As Long

'pass an empty variable into which the API will
'return the flags associated with the connection
Call InternetGetConnectedState(dwflags, 0&)

'return True if the flags indicate a modem connection
IsNetConnectViaModem = dwflags And INTERNET_CONNECTION_MODEM

End Function


Private Function IsNetConnectViaProxy() As Boolean

Dim dwflags As Long

'pass an empty variable into which the API will
'return the flags associated with the connection
Call InternetGetConnectedState(dwflags, 0&)

'return True if the flags indicate a proxy connection
IsNetConnectViaProxy = dwflags And INTERNET_CONNECTION_PROXY

End Function


Private Function IsNetConnectOnline() As Boolean

'no flags needed here - the API returns True
'if there is a connection of any type
IsNetConnectOnline = InternetGetConnectedState(0&, 0&)

End Function


Private Function IsNetRASInstalled() As Boolean

Dim dwflags As Long

'pass an empty variable into which the API will
'return the flags associated with the connection
Call InternetGetConnectedState(dwflags, 0&)

'return True if the flags include RAS installed
IsNetRASInstalled = dwflags And INTERNET_RAS_INSTALLED

End Function


Private Function GetNetConnectString() As String

Dim dwflags As Long
Dim msg As String

'build a string for display
If InternetGetConnectedState(dwflags, 0&) Then

If dwflags And INTERNET_CONNECTION_CONFIGURED Then
msg = msg & "You have a network connection configured." & vbCrLf
End If

If dwflags And INTERNET_CONNECTION_LAN Then
msg = msg & "The local system connects to the Internet via a LAN"
End If

If dwflags And INTERNET_CONNECTION_PROXY Then
msg = msg & ", and uses a proxy server. "
Else
msg = msg & "."
End If

If dwflags And INTERNET_CONNECTION_MODEM Then
msg = msg & "The local system uses a modem to connect to the Internet. "
End If

If dwflags And INTERNET_CONNECTION_OFFLINE Then
msg = msg & "The connection is currently offline. "
End If

If dwflags And INTERNET_CONNECTION_MODEM_BUSY Then
msg = msg & "The local system's modem is busy with a non-Internet connection. "
End If

If dwflags And INTERNET_RAS_INSTALLED Then
msg = msg & "Remote Access Services are installed on this system."
End If

Else

msg = "Not connected to the internet now."

End If

GetNetConnectString = msg

End Function

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