If you control both the local and remote side fully and know how to do networking: OpenSSH not only offers L3, but also L2 network tunnels. Before Wireguard, I

If you control both the local and remote side fully and know how to do networking: OpenSSH not only offers L3, but also L2 network tunnels. Before Wireguard, I had been using this feature for years for ad-hoc and not so ad-hoc tunneling. Can be wired up easily using ip-route and ip-rule on Linux. Use systemd units for connecting and reconnecting.