Here is mine https://gist.github.com/jeena/6179470a8d616455f30635a5c71f5f64 which had a similar problem with the comments, although I couldn’t post comments on my own instance either.

For me the thing was that I had to add:

map $http_upgrade $connection_upgrade {
    default upgrade;
    ''      close;
}

and

        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection $connection_upgrade;

And also change the nginx in the docker to port 8080 so my normal nginx could keep running on 80 and handle all the ssl certificate stuff.

My setup is:

Browser -> native Nginx -> docker Nginx -> lemmy

Oh I was just listening to a podcast where you were a guest in https://pod.fossified.com/2023/04/05/s01e03.html and I had to lough out loud when they asked you what they could do to bring more women into FOSS or what it was and your response was to not invite them to podcasts only to discuss the topic of women in FOSS :D