The contents of this repository is obsolete as PowerShell commands can now do the same.
Take a look at the Add-VpnConnectionRoute PowerShell command to add routes to VPN connections, and use (Get-VpnConnection).Routes to view configured routes.
The default settings on a VPN client sends all traffic over the VPN connection, which "disables" your Internet access.
It is possible to automatically create the required routing rules each time a VPN connection is established, and thus preserve your local Internet access.
Mac, Linux and Unix like OSes use a very simple script stored in /etc/ppp/ip-up.
Windows can do something similar using a PowerShell script and the Task Scheduler.