

You’re being naive. You’re probably not realising how common and well concealed depression is. Then when you see signs you’ve written it off as dark humour that can’t be legitimate feelings because their mask looks happy.
When a coworker was doing the same I had a chat with him, starting the conversation about another friend of mine who had recently attempted suicide and how it was hard for me getting up at 2am to his partner calling me driving to his house and talking him down getting him help and how tired I was. My coworker opened up and told me he had nearly been on the edge too. Completely invisible to everyone at work.
People try to normalise the thoughts that go through their head. Cope with humour and hide with acting normality and energy.
People struggle. Almost everyone goes through depression at some time in their life. You’ll work with people who contemplate suicide and walk by unknowingly everyday.
404 is a web server response suggesting that a web server is up. It’s what’s giving 404.
The web server can’t find your page or document or resource. So one of your web servers (on either the reverse proxy or the actual server) is pointing to the wrong spot on what to serve.
You haven’t tried launching a wrong server on the same port right? Or misconfigured your nginx translation?
Isolate the issue. Ignore nginx and start testing just the web server on the destination and see if the server is giving 404 and then if it is giving the right document then it’s nginx configuration. If it’s not giving you the document nginx can’t serve.
But either way start isolating the problem into the smallest area. And focus on the configurations and files that are related to it.