So it’s actually going against those assumptions that I’m looking for in this discussion. What if it isn’t any of those? What if it’s more like the telegraph? What happens when you start putting interesting limitations on the tech and its use? Everyone, even many modern novelists, tend to just keep it as a generic internet, or phone system (which allows you to run a basic internet), just faster than the fastest ships available. What if it’s the high tech equivalent of messenger pigeons? (Charles Stross had this, with entangled pairs of quantum bits that got used up and had to be shipped by STL ships).

One of the more interesting models I saw was EVE Online - lorewise, the ansible was made of a paired array of entangled hydrogen atoms that transmitted electrical signals between them. This forces a model based around a client array onboard, with the service array being connected in a server rack to a switchboard. Network topography becomes an important part of warfare. The limitations placed on the model drives stories based around dealing with them.