Blazor WASM Client and Server CORS Error .Net6

when i use in the Blazor WASM Client the Code

var client=new HttpClient();var xyz=client.GetAsync(URL);

i got a CORS Error.

when i add an image with the URL i got also the same Error

<img src="@URL" />

I try it also in the API. On Localhost i got my httpclient response. When i upload it on my server i got a timeout Message.

Thank you for your support?

var client=new HttpClient();var xyz=client.GetAsync(URL);