What kinds of VPN connection?
Can you provide the current topology?

M Diamond wrote

What kinds of VPN connection?
Can you provide the current topology?

The topology is simple:
The TP-LInk device will be connected to the ADSL line.
I'll have an ethernet connection to Powerline adapters connecting one PC and a NAS, these devices do not need to use the VPN.
I'll have a wireless network with various media streamers, iphones, ipods and ipads connected to it.

What I'd like to achieve:
I want all traffic from selected wireless devices (chosen by MAC / IP / Other better method) to be routed through the VPN.
All other traffic should not be routed through the VPN.

This is a setup for a family friend and I'd like to be able to say that this one device is always connected through a secure channel, for banking etc.. regardless of the setting son the device which may be inadvertently switched off.

Thanks for your response, I hope the above clarifies what I would like to achieve.

Both D7 and D9 supports VPN passthrough and IPsec VPN only, which doesn't seem like what you need...
How did you make it work in your existing router? Do you remember it?