How to conect vb.net application from online ms access database

This might work for you
Dim connectionstring as String="Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Server.MapPath(mydatabase.mdb);"

On a webserver it would be ideal to use Server.MapPath function. Instead of this you can also try absolute path.
There is CodeProject article too, its in C# though but it might help you out.
How to link to an Access Database in a C# Application[^]

Best Regards,
Ashish

Access databases only work over Windows Networking, not over HTTP. There is no connection string that will allow you to work with an Access database over HTTP through a web server.

Either your clients have to be able to get at a share folder on the server or you'll have to wrap all database access in a web service or you cannot use Access and must switch to a real database engine, like SQL Server.