Ok, I try to clarify things a little bit. I have one computer where my program is installed. The database that is used by my program is in the same directory as my program.

Then I shared this folder where my program and my database are located to local area network. Then I accessed this folder from another computer on my LAN network and made a shortcut of my program to that computers desktop.

Launched the program, data is nicely inserted to datagridview. I can filter data by sql statements. Now I open another form in my program which is used for editing: edit the data, hit "Save" and the messagebox pops up saying: "Can't connect to database!" (I set this exception when I was coding my program). Same thing is with adding new record form. I use datasets, adapters and bindingsources that wizard has set up.

Code for saving after editing:
Code:
Try
        
            'Me.Validate()
            Me.TableBindingSource.EndEdit()
            Me.TableAdapterManager.UpdateAll(Me.TableDataSet)
            MsgBox("Saved successfully!", MsgBoxStyle.Information, "Catalogue")
        
        Catch ex As Exception
        MsgBox("Can't connect to database!", MsgBoxStyle.Information, "Catalogue")
        End Try

Code for adding new row:
Code:
 Try
        

            MainForm.TableAdapter.Insert(Me.ComboProfiil.Text, Me.PikkusTextBox.Text)

            MainForm.TableAdapter.Fill(MainForm.TableDataSet.Table)
            MsgBox("New item saved successfully!", MsgBoxStyle.Information, "Catalogue")
Catch ex As Exception
        MsgBox("Can't connect to database!", MsgBoxStyle.Exclamation, "Catalogue")

        End Try