404 on /admin

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1 
  host: env('HOST', '0.0.0.0'),
  port: env.int('PORT', 1337),
  proxy: true,
  app: {
    keys: env.array('APP_KEYS')
  },
  url: env('URL', 'localhost:1337')
});

my env:

HOST=0.0.0.0
PORT=1337```

I have deployed strapi using docker and cloudflare tunnel

the main page is loading correctly. However the /admin page returns 404 error - in browser console i see:
```GET https://mystrapidomain.com/localhost:1337/admin/main.588aac85.js net::ERR_ABORTED 404 (Not Found)```

How can i change this behaviour of adding localhost:1337 into url?

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2

this part maybe ? url: env('URL', 'localhost:1337')