Repair and constant maintenance of API on WordPress website

We are using the standard WordPress API, which integrates our website to the Android app, feeding it with blog-style posts (text, category, title, image, etc.). However, it seems that it is somehow “blocked” – it does not respond. Maybe there’s something wrong with the recently installed registration plugin. The APP needs to consume the API directly. We need someone, who charges per hour worked, able to correct this problem, and available for maintenance whenever necessary. Can you read the code and estimate the repair cost?

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