One VPN tunnel is up, but a remote subnet is unreachable and absent from learned routes. IPsec parameters are valid. Which approach best fits?

1. Use a supported equal-cost multipath routing design.
2. Set and test supported routing priorities and BGP attributes for the intended preference.
3. Configure redundant HA VPN tunnels across the required interfaces and peers.
4. Inspect BGP advertisements, learned routes, and relevant route scope.