how to force VPN (PPTP) over certain interface?

[SilverNodashi]

Hi,

Is it possible, at all, to force a PPPTP VPN over a given interface?

Let me explain the scenarion: A remote branch (to far to get to quickly) has a VPN over ADSL connection which is very slow. So I told them to buy a LTE router and use that to re-route some of the traffic over the LTE, and thus ease-off some of the load on the ADSL VPN.

The problem is, I need to connect back to the same VPN on this side (IP range 192.41.100.0/24) from that side (IP range 192.168.4.0/24).

I suspect the VPN connects over the pre-existing ADSL line, instead of the new LTE.
My routes are as follows:
pptp 0
LTE 1
ADSL 5

[SilverNodashi]

@JammieR

A vpn has certain limits over portocols and features. Like not all the vpn are offering PPTP or Openvpn protocols.
But PPTP is a protocoll that is built in in every vpn service.
I would advice to use a new vpn for remote locations.

That isn’t possible at this stage. I don’t have control over the underlaying ADSL VPN and need to use this setup for the next 3-6 months when a new Fiber line gets installed. So I’m trying to make the best of what I can, with what I have.

[ebreyit]

Use routing marks.

Mark the traffic intended for the IP of the remote VPN endpoint such that in the routing table you route it via the intended WAN connection (The LTE Connection)