separate VPN route

[markfoodyburton]

I've been struggling with the following.

I have a router (192.168.1.1) that knows about some internet accesses, and wants to route those via a specific VPN to the 'internet' (for convenience I include the 10.0.44.4/24 network in that traffic - see below).
192.168.1.1 handles routing for the 192.168.1.1/24 network, but it has no external routs itself, it routes outbound 'internet' traffic via a dedicated openMPTCP router (192.168.1.176).
The VPN (Wireguard) is configured on the openMPTCP router which has a specific VLAN interface (192.168.44.100/24) just for this 'special' traffic, and has a WG interface (10.0.44.2/24 which connects to 10.0.44.1 at the other end).

From a machine on the 192.168.1.1/24 network I can, indeed, ssh to 10.0.44.1.

However, traffic outside of the 10.0.44.1/24 network is always routed via the 'standard' tun0 interface in OpenMPTCP.
I've tried setting up specific rules, even trying to use the 'marks' as an enabler for those rules, but I have so far not managed to find a solution.

I'd really appreciate some help in building this setup! THANKS in advance.