Invalid grant when requesting a token

Hello !

I'm using a java application to connect to Aras innovator but i encounter a problem i can't seem to fix when using a remote instance of Aras Innovator.

I followed the steps provided here : https://community.aras.com/b/english/posts/token-authentication-using-the-rest-api.

When in a local context, absolutely no problem, i can get the token and do whatever i want with it. But once i'm trying to connect to the remote instance (located on a aws server), i'm getting this error :

{
    "error""invalid_grant",
    "error_description""Object reference not set to an instance of an object."
}
In Postman, my parameters are the followings : 
They are the same as for the local connection since only the address of the OAuth server is changing.
What can i do ?