Hello dear friends,
I am using the Vigor 3900 in a producation facility with about 40 VPN (IPsec & SSL) users connecting and working remotelly. The router itself has a nice reporting GUI but in case of reboot all the info is lost and starts from beginning. Also you can see the history of vpn connections per user but you cannot just click a date of a month and see what users conencted and their duration.
In my quest for a complete reporting tool that will allow me to feed the daily syslog files saved to router's usb port and accessed via ftp) and the produce a nice and searchable report so I can be aware of who connected and when, I approached some companies known for their syslog reporting products.

Unfortunately I had no luck but Fastvue ( http://www.fastvue.co ) company created for me a script on GitHub that can do something similar. It is available here
https://github.com/Fastvue/draytekvpnanalyzer

Nevertheless I have contracted a private software developer and in about 10 days I will have my own reporting tool (based on Excel with VBA). This tool will take all the daily syslogs located in a folder, batch feed them and produce a nice graphical report of users connection and duration. The report can be used both by date, by date period and by user.

When I have this tool I will happily share that with you also.
Best Regards

I am happy to report that the Excel tool is ready

https://www.dropbox.com/s/vi458c2z6qr5pws/DraytekVPNLog.zip?dl=1

Just put all the logs in a folder, fire up the Excel and ..instructions are included, along with password to modify the VBA.

Macros need to be enabled and for non- english PC users, format of region must be set in English (world, or UK)
Tested with Excel 2016 (might be compatible with 2013, try..)