Can not reach external login page event listed in walled garden

Dear All

I’m writing a python based centralized Hotspot login page.

To make a test, I prepare one HapLite as Hotspot.
Put my server address in walled garden, also facebook and gmail site on it.

When I try to connect to this hotspot, I got error as attached picture.
But as expected, I still open facebook and gmail.
redirecterror.jpg
I check my server Nginx (as reverse proxy to my app) logs … there is no error.
I run my app in debug mode, and also there is error shown.

Actualy, on Nginx logs and App debug … there is no Access detected.

I try to open my app via android browser … and it’s opened without problem.

Kindly please give me some clue