We have sharepoint enabled with both form and windows authentication for the same try to establish REST connection but we are geting error i have mentioned in my post then we tried same settings of connection by disable form authentication in sharepoint and connection was succesful, but our team need form authentication as well in sharepoint. I'm sure at this moment it was more of sharepoint issue than qliksense but i'm writing here to know expereinece of others.
I am also facing the same issue. I have tried the method from the link below but still no luck. Getting the same result 'HTTP protocol error 403 (Forbidden): The server refused to fulfill the request'. Have you found any solution?