Frontend-Backend Connection Troubleshooting

I have a frontend that has been installed, but it won't connect to the backend, which is using Node.js. I have full access to the backend server. I need an experienced developer to troubleshoot the connection issues and ensure proper installation. Skills required include:
- Proficiency in Node.js
- Experience with frontend-backend integration
- Troubleshooting skills
- Communication skills

NPM & Node & Nginx & Git

Python 3.9.21

python3-venv