four of them (9-12) are from the first batch that i had acquired one o two years ago
and two (14-15) were added some weeks ago after the fault of a plug (node13)
I do not understand why they stay apart in the graph below.
the sockets are very close, max dist.2-4 meters, but why are the nodes 14-15 in a separate branch?
The probable reason it is so odd is that the heal may have failed. This is now reported as fixed in the latest release of the binding.
Even then it is worth considering that the diagram may still be missing connections that do work. The diagram reflects nodes reported during a heal. As the heal test for neighbours at -6db it does not necessarily get all nodes in range. It does get those that responded.