Right, I’ve moved to my PC and your post makes more sense now.

It seems like the problem section of your logs is couldnt_find_object: error decoding response body: missing field properties at line 1 column 158. I’m thinking it may have something to do with your ngnix.conf because it might be implying that it can’t see anything at all, rather than just a missing field property.

I’ve shared my nginx.conf below in the hope that, by comparison you can get your instance to federate. (This is from my instance that is federating fully and correctly).

worker_processes auto;
events {
    worker_connections 1024;
}
http {
    upstream lemmy {
        # this needs to map to the lemmy (server) docker service hostname
        server "lemmy:8536";
    }
    upstream lemmy-ui {
        # this needs to map to the lemmy-ui docker service hostname
        server "lemmy-ui:1234";
    }

    server {
        # this is the port inside docker, not the public one yet
        listen 1236;
        listen 8536;
        # change if needed, this is facing the public web
        server_name localhost;
        server_tokens off;

        gzip on;
        gzip_types text/css application/javascript image/svg+xml;
        gzip_vary on;

        # Upload limit, relevant for pictrs
        client_max_body_size 20M;

        add_header X-Frame-Options SAMEORIGIN;
        add_header X-Content-Type-Options nosniff;
        add_header X-XSS-Protection "1; mode=block";

        # frontend general requests
        location / {
            # distinguish between ui requests and backend
            # don't change lemmy-ui or lemmy here, they refer to the upstream definitions on top
            set $proxpass "http://lemmy-ui";

            if ($http_accept = "application/activity+json") {
              set $proxpass "http://lemmy";
            }
            if ($http_accept = "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\"") {
              set $proxpass "http://lemmy";
            }
            if ($request_method = POST) {
              set $proxpass "http://lemmy";
            }
            proxy_pass $proxpass;

            rewrite ^(.+)/+$ $1 permanent;
            # Send actual client IP upstream
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header Host $host;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        }

        # backend
        location ~ ^/(api|pictrs|feeds|nodeinfo|.well-known) {
            proxy_pass "http://lemmy";
            # proxy common stuff
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "upgrade";

            # Send actual client IP upstream
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header Host $host;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        }
    }
}