Error when assembling chunks. Status code 504 on big file upload

I’m just putting this here for people in the future who may be having this issue. Although I’m not using a plain ngnix docker container as my reverse proxy, I am using the Nginx Proxy Manager container to do all of my reverse proxy needs. I’ve been working on this for days trying to figure it out and tried all of the same things everyone else has tried until I saw a post on an Unraid forum. Adding these lines to the proxy config for Nextcloud fixed my issue

   proxy_connect_timeout 1d;
   proxy_send_timeout 1d;
   proxy_read_timeout 1d;
   send_timeout 1d;

Basically all this does is increase the timeouts on the nginx side to 1 day instead of whatever the default may be. Obviously this is probably way more than it needs to be, but it fixed my problem.

edit: Also just for clarification, this was in addition to the lines listed in the original post.