remotely served Django service, does not return response for PATCH requests – Nginx

I have deployed a Django rest framework service with multiple APIs on my Ubuntu 20.04 server with Gunicorn, everything works fine, but PATCH requests from outside the server do not receive a response, although the application receives the request and fully processes it.
I have even tested it with Django runserver and the problem remains and has nothing to do with Gunicorn.
Steps to reproduce:

1. On the server we create a new Django application:

ssh to_my@server
python3 -m pip install django
django-admin mytest
cd mytest
python3 manage.py runserver 0.0.0.0:9999

2. On the server trying to send requests to the application:

ssh to_my@server
curl --request GET localhost:9999/ # this works fine and we can see the response
curl --request PATCH localhost:9999/ # this works fine too

3. On another machine try these:

# on my local machine
curl --request GET IP:9999/ # this works fine
curl --request PATCH IP:9999/ # **** this will get a `curl: (56) Recv failure: Connection reset by peer` after some times

The response never arrives although in the console you can see that the request is fully received and Django has no problem:

Invalid HTTP_HOST header: '207.154.246.122:9999'. You may need to add '207.154.246.122' to ALLOWED_HOSTS.
Bad Request: /
[02/Nov/2021 11:18:25] "PATCH / HTTP/1.1" 400 62827

Please ignore the Exception it has nothing to do with our problem.
Note that this is a minimal deployment, I am serving via HTTP not HTTPS and the port is already open, I know I can use PUT instead of the PATCH method, and I am not using NGINX just forwarding it directly.
My question is: what is causing this behavior? is this the operating system? and how I can solve this problem and receive the response from my PATCH requests?