Reverse proxy with Worker problems with ports

I’m trying to do a little reverse proxy with workers, but I’m having some troubles.
Enviroment:
I have a service running on https://my.domain.com:2053, but I want to access it from https://my.domain.com:443 with cloudflare.

What I do:
I have a worker with this code:

addEventListener('fetch', event => {
  const request = event.request;
  var url = new URL(request.url);
  url.host = url.hostname + ":2053";
  event.respondWith(fetch(url, request));
});

Problem?
At first of all, it works, but the problem is that the forwarded hostname is with the port 2053, and all links that it respond to me have the port 2053, not the 443.

Is there anyway to solve this? like rewritting the a href and all links etc.

I’m not programmer so i appreciate simple answers.