I’m having a setup in which i establish an SSTP tunnel to a remote site and have a route set to reach the remote subnet (192.168.168.0/24 here) through that tunnel - works fine

However, at random intervals, I lose my setting - the route reverts to an “unknown” gateway and obviously traffic stops.

This might be triggered by the tunnel disconnecting (have to confirm) but in any case, I’d like to route to stay, no matter of the tunnel’s state. Interestingly enough this is happening only with this specific route/tunnel combo. I have a dozen other similar setups in the router (ie SSTP tunnel + route) and they never “disappear” as this one.
Any idea/suggestion welcome!