Suggestions for best method of failover

Hi

I’m after some advice on how to design my setup for a remote van to connect back to head office.

What I have is some vans, (RB1100ahX2 ROS6.20, draytek 120 ADSL/pppoe) connecting back to head office (RB1100ahx2 ROS6.6)

We have configured so far :
Van does ADSL PPPoE Dial to internet
Van does OVPN back to head office
each van gets a /24 (10.0.x.0/24) - OSPF takes care of the routes
two vans can sit side by side, plug in to each other and OSPF provides shortest path first

This all works great, everybody is happy.

Sometimes we have no ADSL, so I have one port configured for DHCP client, van plugs into internet from somewhere, then OVPN happens, then OSPF happens.

Sometimes we have both ADSL, and the internet from the DHCP client connected. This is the scenario I am working to improve now.
Currently, I put a higher distance on the DHCP client than the PPPOE interface, so it will use the ADSL first, if that fails, eventually the OVPN will redial on the DHCP interface and come back to life.

I want to make this a faster better switch.

Currently looking at doing two OVPN connections (one via ADSL one via DHCP interface) and running OSPF + BFD to allow for faster failover.
Not sure how I would make one OVPN connection route out only one interface..
Is this the best option? What about bonding the two interfaces? Problem is the ‘unknown internet’ is sometimes 100M fiber and other times a 3g modem.

Thanks for your advice.

ok so I think I need to run another OVPN server at the head office, on a different ip or port. That way I can use ip firewall to mark packets to the second OVPN server and route those out my second connection…

But I don’t think you can run two instances of OVPN server on one routerboard? Perhaps with metarouter but thats a pain… Really just want one on port 1194 and nother on port 1195