Where do I get a m/c certificate to make L2TP calls?

Hi Folks,

Every time I bootup my Event Viewer's System Log gives me 8 Remote Access server errors + 1 Remote Access warning, and I really need your help to fix please.

8 errors are the same:
Event ID 20082 saying the Remote Access Server is unable to reset lana on line....(then there's one numerical entry for each of the 8 errors).
Where LANA means Local Area Network Adapter number.

Two seconds after these errors are logged there appears this (edited) Warning:
Event Type: Warning
Event Source: RemoteAccess
Description:
A certificate could not be found. Connections that use the L2TP protocol over IPSec require the installation of a machine certificate, also known as a computer certificate. No L2TP calls will be accepted.

Any ideas how to fix, my friends?

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