I'm trying to use axios to make a post request to my backend. Every time I make the request I was receiving this error:

origin 'http://localhost:1234' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

So I added the appropriate header:

const FRONTEND_URL = 'http://localhost:1234'

export async function connect( address:string | undefined, signature:string | undefined ) {
        const url = `${SERVER_URL}/connect`;
        return await axios.post(
          url,
          { address, signature },
          {
            headers: {
              'Access-Control-Allow-Headers': '*',
              'Access-Control-Allow-Origin': `${FRONTEND_URL}`,
              'content-type': 'application/json',
    
            },
          }
        );
      }

I still get the same error. Why isn't it detecting my Access-Control-Allow-Origin header? (I've restarted servers multiple times)

https://masteringjs.io/tutorials/axios/post-headers