WordPress hangs on Update post/page – nginx proxying to apache

I noticed a few days ago that when I try to publish/update a post or a page the page hangs. When I access apache on port 8080 it finished quickly.

It probably has to do with some nginx buffers but I am still trying to find what’s the cause.

Not sure what has changed on the WP’s end.

I’ve posted the question here as well.
https://digitalocean.com/community/questions/nginx-keeps-buffering-post-requests