This is a third thing–having devices at home reach devices behind the slate.

So if the slate is connecting as a client to your home 68U Openvpn server, “Lan Only” on the 68U will allow devices behind the slate to reach devices on your home network by pushing the route. It won’t push a new default gateway, so your slate devices should continue to reach the internet as before. For devices behind the 68U to reach devices behind the slate, you have to have the 68U add a route to the slate’s network when it connects.