Draytek LAN to LAN VPN setup guide is available here:
Category Archives: VPN
Stop web traffic using VPN – Windows XP, Windows 7
Right click the connection, and choose Properties.
Click “Networking” Tab
With TCP/IP selected, hit “Properties”
Click “Advanced”
Untick “Use default gateway on Remote network”
Source: Superuser
VPN connects but drops out on Vista
Disable QoS Packet Scheduler on the network interface
Source: Technet