App can't send HTTP requests to specific URL if unless open the URL through webview

I have HTTP request bug but I can’t find any problem on my app .
And it works on Appgyver preview. But doesn’t work on actual app.

If the app tries to send HTTP request to specific URL before open it on webview, returns “Unknown Error”.
After open the URL on webview, HTTP request works.
I couldn’t find reason of the bug… Really thank you for your helps!