API is not working when change domain and hosting

I download a flutter app source code from github which is use to fetch some data from a specific website. After downloading, I run that app in android studio and everything was perfect. Now, I just download the website source code and host that code on my hosting and connect my own domain. But the problem is that, when I replace the demo website url to my own website url into flutter app then the app is running but it is not able to fetch data form my own website. For kind your information I can say that, there is no problem with the website because since I just copy paste the source code then the website is fully same with the demo website. I think the problem with cpanel. Any one can fix my problem?