Large files are not transmitted to an Elastic Beanstalk hosted app - node.js

Question

I am currently working on a web application where I need to store large files (mp4 videos that sometimes have a size greater than 100mb). But, when I am trying to upload them from a static Angular website hosted in a S3 bucket to an API hosted with AWS Elastic Beanstalk, I got a error that I don't understand.
Click here to see the error
What I tried:
There is no problem when uploading PDF. It works perfectly.
There is no problem when uploading very short MP4 (3s, 453Kb). It works clean, but a little bit slower than PDF, but still really short (3 seconds). This is why I think the problem could came from the file size.
I read on Internet that there's something called client_max_body_size when using Nginx (as AWS does). I tried to increase this default limit by adding this to my project:
myrootproject/.ebextensions/nginx.conf
Into nginx.conf:
files:
"/etc/nginx/conf.d/proxy.conf" :
content: |
client_max_body_size 4G;
but nothing has changed... or at least it didn't have the desired effect, it still not working.
Additional informations
When I do this manipulation in local, it works fine.
When I do this manipulation from the hosted website (S3 bucket) to localhosted API, it works fine.
It takes really long to have a response from the server (only when this error occurs). I have the feeling that the request don't even access my NodeJS code, because if an error is emit on it, I would handled it.
Here is screenshots of my request, if it could help:
Request (first part)
Request (second part)
I really need help on this one, hoping you can give it to me!
P.S: I created this post with help of a translator. If some parts are strangely written, my apologies,

Answer 1

The option myrootproject/.ebextensions/nginx.conf does not take effect, probably because you are using Amazon Linux 2 (AL2) - I assume that you are using AL2. But this config file works only in AL1.
For AL2, the nginx settings should be provided in .platform/nginx/conf.d/, not .ebextentions. Therefore, for example, you could create the following config file:
.platform/nginx/conf.d/mynginx.conf
with the content of:
client_max_body_size 4G