I’m not saying this is it; but it could be a candidate.
https://en.wikipedia.org/wiki/Wireless_mesh_network.
Ham radio guys sometimes run such nets for emergency communications purposes, and don’t widely announce it to help a bit with some security.
-73-
For example…. The California forests have been very prone to destructive forest fires in recent years. I can see a high utility use for fire fighters to have mesh networks to supplement their conventional communications where there are blind spots because of topography.
I have a problem with the idea that the function and sources of the so called mysterious devices is not known. This information may not be known to the reporter and his sources. However, there are civilian and government geeks that can determine the technical functions of the devices very easily. With more time, forensics into the electronics and programming can peal back the layers to expose the who and why in detail.
My opinions…