I followed the docker installation instructions and added the certificate successfully but I get this status:

400 Bad Request | nginx

host nginx error logs:

2023/06/11 12:12:45 [debug] 10161#10161: *16 http upstream process header
2023/06/11 12:12:45 [error] 10161#10161: *16 connect() failed (111: Connection refused) while connecting to upstream, client: 198.199.109.53, server: mydomain.tld, request: "GET /version HTTP/1.1", upstream: "http://127.0.0.1:82/version", host: "xxx.xxx.xx.xxx"
2023/06/11 12:12:45 [debug] 10161#10161: *16 http next upstream, 2
2023/06/11 12:12:45 [debug] 10161#10161: *16 free rr peer 2 4
2023/06/11 12:12:45 [warn] 10161#10161: *16 upstream server temporarily disabled while connecting to upstream, client: 198.199.109.53, server: mydomain.tld, request: "GET /version HTTP/1.1", upstream: "http://127.0.0.1:82/version", host: "xxx.xxx.xx.xxx"

I replaced my host IP and domain for privacy

Please see my comments below for more info. I tried putting all text here in the body but it won’t let me post.

EDIT: It is now fixed! What I did is replace the following line in my host nginx:

location / {
         proxy_pass http://localhost:82;
         proxy_set_header Host $host;  <---- replace this
         include proxy_params;
    }

With this:

location / {
         proxy_pass http://127.0.0.1:82;
         proxy_set_header Connection "keep-alive, Upgrade";
         proxy_set_header Upgrade websocket;
         include proxy_params;
    }

And thanks to @frozen@lemmy.frozeninferno.xyz who pointed me in the right direction to allow search to other instances:

networks:
  # communication to web and clients
  lemmyexternalproxy:
  lemmybridge:  <<----- added this
  # communication between lemmy services
  lemmyinternal:
    driver: bridge
    internal: true

services:
  proxy:
    image: nginx:1-alpine
    networks:
      - lemmyinternal
      - lemmyexternalproxy
      - lemmybridge  <<----- added this

  lemmy:
    image: dessalines/lemmy:0.17.3
    hostname: lemmy
    networks:
      - lemmyinternal
      - lemmybridge <<----- added this