CORS Error Fix for React App

I need help resolving a CORS error on my application. The app is made using React and the database is MongoDB, deployed on separate servers.

Requirements:
- Fix CORS issues on both frontend and backend
- Address specific APIs or endpoints causing the error
- Handle both GET and POST request issues

Ideal Skills:
- Experience with CORS configuration
- Proficiency in React and Node.js
- Familiarity with MongoDB and server setups

Please provide a detailed plan and timeline.