RestClient sends requests to all nodes in succession, and there are extensive tests for this.
A common cause for the problem you describe is to have a new RestClient created for each request. Every new client starts with the first node, causing the issue. It also slows down the application a lot since RestClient is a heavyweight object.
Can you check this? The RestClient should be a singleton object that is reused for all requests, and not created anew every time.