If you're having problems with a local copy of stable diffusion experiencing a connection timeout.

I've solved it by allowing websockets in my nginx proxy, like so: 

I spent way too much time on this not to share the solution. : ) You can find the tl;dr at the bottom.

The problem appeared to be a lag, but since none of my components are top of the line, I wasn't sure where exactly the problem was. Was it the Intuos tablet, or something else? I suspected the software, Krita, and spent some time tinkering with it, configuring caching, and adjusting rendering configuration. That didn't help.