Option Explicit On
 
Public Class Form1
    Private Const laufwerk = "Z:\INT\Data\CustomerSolutions\Systems\DE_SY\"
    Private Const ordner = "\A\1. Projektierung\1.7 Angebote"
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        Dim v$, folder$, path$
 
        v = TextBox1.Text
        If Len(v) > 1 Then
            'If Left(v, 1) = "!" Then
            v = Replace(v, "!", "")
            folder = Left(v, 4) + "xx"
            path = laufwerk + folder + "\" + v + ordner
            Shell("explorer.exe " + path, vbNormalFocus)
            'End If
        End If
    End Sub
End Class

Option Explicit
Private Const laufwerk = "Z:\INT\Data\CustomerSolutions\Systems\DE_SY\"
Private Const ordner = "\A\1. Projektierung\1.7 Angebote"
 
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
Dim v$, folder$, path$
 
    v = Target.Cells(1, 1).Value
    If Len(v) > 1 Then
        'If Left(v, 1) = "!" Then
            v = Replace(v, "!", "")
            folder = Left(v, 4) + "xx"
            path = laufwerk + folder + "\" + v + ordner
            Shell "explorer.exe " + path, vbNormalFocus
        'End If
    End If
End Sub