ASU server: access to xmlhttprequest has been blocked by cors policy

I installed my own ASU server based on the guide here, but creating a new image doesn't work. I become the following error in the browser when I request an image:

Access to XMLHttpRequest at 'http://<server_IP>/api/v1/overview?1745428639689' from origin 'http://<router_IP>' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

GET http://<server_IP>/api/v1/overview?1745428639689 net::ERR_FAILED 301 (Moved Permanently)
(anonymous) | @ | luci.js?v=25.111.775…4aa1d-1745362806:59
(anonymous) | @ | luci.js?v=25.111.775…4aa1d-1745362806:40
Promise.then
request | @ | luci.js?v=25.111.775…4aa1d-1745362806:40
get | @ | luci.js?v=25.111.775…4aa1d-1745362806:64
handleCheck | @ | overview.js?v=25.111…4aa1d-1745362806:21
eval | @ | ui.js?v=25.111.77565…aa1d-1745362806:368

Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'ok')
at eval (overview.js?v=25.111.77565~1b4aa1d-1745362806:21:1728)
eval | @ | overview.js?v=25.111…4aa1d-1745362806:21
Promise.then |  
handleCheck | @ | overview.js?v=25.111…4aa1d-1745362806:21
eval | @ | ui.js?v=25.111.77565…aa1d-1745362806:368

When I paste the 'http://<server_IP>/api/v1/overview?1745428639689' in the browser, then I become the result on the following url: 'http://<server_IP>/json/v1/overview.json'.

Start with the ASU server installation guide and trace the /api/v1/overview request that redirects to /json/v1/overview.json. Check how the server handles requests from the router origin and compare the browser request with the server response. Done means creating a new image works without the CORS or undefined-response errors.