What's the Name of That Book??? discussion

You guys helped me once before figure out the Across the Nightingale Floor series, so I'm hoping you can help me again.

I originally read the first in this series between 2006 and 2013 (tentative dates, not really certain). The second book was yet to be published at the time of reading, and I lost the note that I had about the title. I believe the title was one word, and one of the books in the series may have started with an O.

It's your basic space series - a "union" of planets in a territory, with outlying planets facing their own struggles and poorly resourced. The main world of the union faces an attack towards the end of the novel. One of the main characters is banished to a colony world, on which they begin to find alien life-forms, but then the first book ends. Humans are the main species in the novel with no alien races until the end (I believe, this might be a red herring).

Two characters, a couple, maintain a specific section of the "rail" network linking planets, and I believe the rail network is attacked, killing one of them, and stranding the other, who then waits for death.

The rail network isn't the only means of transport, I believe there are ships but I don't know if FTL travel features.

I've also posted on Reddit, and some unsuccessful suggestions so far have been Pandora's Star, Illuminae, and Dispossessed,

I really hope you guys can help me, I've been wanting to find this for ages!

Oliver ~~
You can "bump" your thread every month or so. This pushes your thread back to the top of the folder instead of languishing here on page 176 where fewer eyes will see it. Get back in the game! Bump!
You can do this by typing a new comment at the end of the thread, or even by typing the word "bump."
Good luck!

Executor Rising (2014) by Rhett C. Bruno? The triology appears to be completed in 2016.

(Google search -- site:www.goodreads.com "science fiction" "rail" connects planets exiled)