Log VPN users

I have a Vigor 2900 series router and can see who is connected by VPN in real time but this does not log/history the username so that I could see who was connected throughout the day.

Does anyone have any ideas or know of a router/device that will log my users?

Username and passwords are configured within the Vigor router but I and perhaps many IT Managers would like a nice simple understandable log sheet/page to check the days connections.