I’ve create a website for a travel agency.
The stacks are Angular for front-end and nodejs for back-end (the API).
For different services, users of the website submit a form and the agency receive data of the form through mail. I’ve donne it with mailgun in the back-end.

The problem is that i have publish both front-end and back-end on production on a french server named “O2switch” and every think work fine for me, but the website have been tried by many persons leaving in Africa and for them the submition of form generate errors.

CORS ERRORS. (how i know it’s cors problem ? A user from there have shared the screen when manipulating the website and i’ve told him to do some manipulation with the inspector of the browser )

In the back i have clearly deal with cors, and i have only whitelist request coming from the front-end.

Why is it working fine for me and not for them there in Africa?
If someone could help me.