Precursor [Foreigner 4] by C. J. Cherryh
This book is part of a "Foreigner" group of books by the author. It's the first book in the second trilogy [fourth book in the entire group]. It follows Inheritor.
The Foreigner series of books involves a human starship, Phoenix, which has lost its way - not knowing where in the galaxy it's ended up. They reach an Earth-like planet. A portion of the people end up descending to the ground, the starship goes to explore other stars. The planet already has a native race that's more-or-less humanoid in physical terms, if not thought. Communication is difficult. The natives and the humans work under different assumptions and conflict results. The humans end up relegated to a single island. The humans interact with the natives through a single diplomat. Initially, the natives had limited technology, but are gaining it from humans via trade for resources. After 200 years, Phoenix returns concerned about hostile aliens from another star system. The books feature an extensive look at an alien society and issues of successful communication with aliens. Much of the story deals with political intrigue and maneuvering.
At this point, the atevi space program has reached the stage they are able to send a shuttle with atevi and human colony delegations to the space station. Bren now acts as a representative of the atevi [or the atevi leader Tabini.] He is sent to the station to negotiate with Phoenix in response to a diplomatic pull-back by the ship. (This after initially promising negotiations with Captain Ramirez.) He must deal more with the ways of the Phoenix.
By this time, Phoenix's liaison to the atevi, Jase, has had much training and has had the opportunity to experience by being on the planet. But Jase and the ship's liaison to the human colony have returned to the ship and are unavailable.
Bren continues to face family issues as well as his professional ones. Factions within each group continue to be a problem. And he finds himself not always in contact with Tabini.
There are more concerns that a hostile alien race that Phoenix previously encountered may be trying to follow them back to the planet. Phoenix needs resources to meet this threat, and that need makes at least part of the crew believe they must work with the atevi and human colony.
The ending is more in anticipation of a sequel than a satisfying ending for a stand-alone novel. This is not a major problem as there are already sequels available. It is not a fast-moving book.