Debugging REST API & MySQL Synchronization

I'm looking for a backend developer to troubleshoot and fix a few issues with an existing web application's API integration.

The application connects to an external REST API, retrieves customer and order information, and stores the data in a MySQL database. Most of the functionality is already working, but there are some synchronization problems that need to be resolved.

Current Issues:
- Some API records are not being saved to the database.
- Duplicate records occasionally appear after synchronization.
- API requests sometimes fail due to timeouts.
- Updated records from the external API are not always reflected in the database.

What Needs to Be Done:
- Review the existing API integration and synchronization logic.
- Identify and fix missing or duplicate records.
- Implement proper handling for API timeouts and failed requests.
- Ensure existing database records are updated correctly.
- Add basic error logging to help troubleshoot future issues.
- Test the synchronization process with sample data.

Technical Details:

The backend uses PHP with MySQL and connects to a third-party REST API using JSON requests and responses.

The existing application and database are already set up. This project is focused on debugging and fixing the integration rather than building a new system.

Expected Deliverables:
- Updated and working API integration.
- Reliable synchronization without duplicate records.
- Source code with the necessary fixes.
- A short summary of changes made.
- Successful testing using sample API responses.

Please briefly explain your experience debugging REST API integrations and working with MySQL databases. Include your estimated completion time.

If the work goes well, there may be additional backend maintenance tasks in the future.