Hi,
If the VPN was set-up in RUT240 and it is not used as the default gateway - it will not be reachable by VPN, as the device is not in the VPN network. The only ways would be connecting the controller directly to IPSec (which I doubt it has), connecting non-RUT240 router to the IPSec VPN network, or going back to the RUT240 gateway.
EB.