As part of a project I'm working on, I've been using nginx on Linux systems for a while.
Currently I'm trying to run it on a Windows system.
When I send a request to nginx (using a browser) it fails, and I get this error message in the error log:

2017/06/26 14:15:56 [info] 34092#16900: *1 client closed connection while waiting for request, client: xxx.xxx.xxx.xxx, server: xxx.xxx.xxx.xxx:4322

Note that this message appears immediately upon making the request, not after some timeout period.
Additionally, the nginx is configured to just return a 400 error code, so nginx isn't trying to proxy to some external server.
I wasn't able to detect any problems in WireShark - SYNs being exchanged, ACK returned, HTTP request, ACK, 2 more SYNs + ACK, then ~30 seconds later the connection closes (FIN).

The relevant config section:
server {
listen xxx.xxx.xxx.xxx:4322;
location / {
return 400;
}
}

Does anyone have an idea of why this happens?