hi... logon to the router's setup page click on the VPN >> VPN client access >> create a username and password and use the same username and password for the VPN client software to connect to the VPN tunnel..
First you have to make sure under your firewall tab the Block WAN Requests is disabled. Then under the VPN tab enable PPTP server and what ever pass through is enabled. Then create a tunnel under the client to gateway>local group setup then set up VPN client access for your users. I have the same router and firmware and it works for me. Make sure when you set up your QuickVPN software you have the correct user/password and WAN IP address to your router.
make sure that the router has the latest firmware and the latest Quick VPN is installed on the client computer .. change the MTU size on the router to 1458 .. the firewall on the client computer should be disabled ... and the VPN passthrough should be enabled on the client-end router ..