Cross-origin request Blocked on LMS server

Hi
I have a local machine running V15 together with LMS.

When I monitor the browser console and I select to view the LMS portal, I keep on getting the following error.

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://<DOMAIN>/socket.io/?EIO=4&transport=polling&t=P3Zyc4l. (Reason: CORS request did not succeed). Status code: (null)

I found this forum-post related to this, but this is an API-call situation. I am not doing API-calls. I just have a standard ERPNext-LMS installation .

(https://discuss.frappe.io/t/cross-origin-request-blocked/24135)

what puzzles me is that there is reference to https://DOMAIN
This is a local machine with no SSL and I am using the hosts-file to resolve.

Can someone please help?