Any given message sent by any node in the network may not take the same route from device to device through the mesh. So really it makes no sense to worry about routes at all except on a message by message basis.
So instead of showing routes, the map shows neighbors. And to be specific, it’s showing which nodes have heard from other nodes at some point recently.
The orange node is the controller.
The yellow nodes are routers. These nodes can forward messages from other nodes on their way toward their ultimate destination.
The solid green nodes are not routers. Battery powered devices typically won’t be routers.
A line from one node to the next indicates that at least one of those two nodes lists the other as a neighbor, at least one of those nodes has seen the other.
A solid line means both nodes list the other as a neighbor. A dashed line with arrow indicates that only one of the nodes sees the other as a neighbor. In the map above node 4 sees node 6 as a neighbor but node 6 does not see node 4 as a neighbor. Does that mean there isn’t a strong signal between node 6 and node 4? Probably not. All we can say is so far is that node 6 hasn’t seen node 4.
So the map can tell you a little about how strong your mesh is. But it doesn’t really tell you much about the routes that any given message will take to get from point a to point b. And it only really shows a little about the mesh’s health. Take the original network above. Nothing is showing node 1 as a neighbor and node 1 lists nothing as a neighbor. If that meant that there was no route between node 1 and the rest of the nodes it would mean nothing in your zwave network would work. Nodes 2-6 would be marked as dead and no messages would get through to openHAB. But clearly messages are getting through between node 1 and the rest of the nodes or else all the nodes would be marked as dead and there wouldn’t be any arrows at all.
If you are otherwise experiencing Zwave problems the map can help diagnose some things. For example when I started out I noticed certain switches took a long time to switch after being commanded, 10 seconds or more. I pulled up the network map (as it existed back then) and I noticed that only one of my ten devices (at the time) listed the controller as a neighbor and everything else listed that one device as a neighbor. That hinted to me that perhaps I had a bottleneck. That theory made some sense as all mains powered devices were on a different floor from the controller and the one device that saw the controller was directly under the controller.
So I did pretty much the only thing you can do when there is a problem with the mesh network; I bought another mains powered device. I put this one on the same floor but in a different room from the controller. Suddenly all the devices on the main floor started listing that new device as a neighbor and all switching would happen instantly.
So coupling the network map with your knowledge about how the devices are physically located can be used together to help you decide where to put another mains powered Zwave device to improve the mesh. But it doesn’t really tell you much more than that and it doesn’t tell you much on it’s own.