Have you seen this support guide re what you can/can’t do on Netlify?
If your server component runs a NodeJS script (e.g.node app.js or something similar) it is unlikely to work as you expect. It is possible to use ExpressJS in a serverless environment such as Netlify, though you would need to rework at least part of the codebase
If you have any further questions, can you share a deploy log, your build settings, and the repository you are deploying from.