HTTP Request not working

Hi There,

I want to post a http reuqest from the Homey to a device.

But i get the following error:
{“error”:400,“msg”:“invalid content-type”,“data”:{}}

Already try content-type:
Content-Type: text/html; charset=UTF-8
Content-Type: multipart/form-data; boundary=something

When i put the url in chrome it works fine.

How to get this working? Thanks.