I replied to your other comment, but most likely cause is the API server not getting the correct client IP. If that's not setup correctly, then it will think every request is from the reverse proxy's IP and trigger the limit.

Unless they're broken again. Rate limiting seems to break every few releases, but my instance was on 0.19.12 before I shut it down, and those values worked.

Thanks! Yes, I saw both messages and I am now going through the NGINX config and trying to understand what could be going on. To be honest, Lemmy is the hobby that taught me what a 'reverse proxy' and a 'vps' are. Answering a question such as 'Are you sending the client IP in the X-Forwarded-For header?' is probably straight forward for a professional but for me it involves quite a bit of learning 😅

At location /, my nginx config includes:

      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

Yeah, you are setting it, but that's assuming the variable $proxy_add_x_forwarded_for has the correct IP. But the config itself is correct. Is Nginx directly receiving traffic from the clients, or is it behind another reverse proxy?

Do you have a separate location block for /api by chance, and is the proxy_set_header directive set there, too? Unless I'm mistaken, location blocks don't inherit that from the / location.

    # backend
    location ~ ^/(api|pictrs|feeds|nodeinfo|.well-known) {
      proxy_pass http://0.0.0.0:8536/;
      proxy_http_version 1.1;
      proxy_set_header Upgrade $http_upgrade;
      proxy_set_header Connection "upgrade";

      # Rate limit
      limit_req zone=mander_ratelimit burst=30000 nodelay;

      # Add IP forwarding headers
      proxy_set_header X-Real-IP $remote_addr;
      proxy_set_header Host $host;
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }

nginx.org/en/docs/http/ngx_htt…

$proxy_add_x_forwarded_for is a built-in variable that either adds to the existing X-Forwarded-For header, if present, or adds the XFF header with the value of the built-in $remote_ip variable.

The former case would be when Nginx is behind another reverse proxy, and the latter case when Nginx is exposed directly to the client.

Assuming this Nginx is exposed directly to the clients, maybe try changing the bottom section like this to use the $remote_addr value for the XFF header. The commented one is just to make rolling back easier. Nginx will need to be reloaded after making the change, naturally.

     # Add IP forwarding headers
      proxy_set_header X-Real-IP $remote_addr;
      proxy_set_header Host $host;
      # proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_set_header X-Forwarded-For $remote_addr;

Thanks!

I was able to crash the instance for a few minutes, but I think I have a better idea of where the problem is. Ths $emote_addr variable seems to work just the same.

In the rate limit options there is a limit for ''Message''. Common sense tells me that this means 'direct message', but setting this to a low number is quite bad. While testing I eventually set it to '1 per minute' and the instance became unresponsive until I modified the settings in the database manually. If I give a high number to this setting then I can adjust the other settings without problem.

"Message" bucket is kind of a general purpose bucket that covers a lot of different endpoints. I had to ask the lemmy devs what they were back when I was adding a config section in Tesseract for the rate limits.

These may be a little out of date, but I believe they're still largely correct:

So, ultimately my problem was that I was trying to set all of the limits to what I thought were "reasonable" values simultaneously, and misunderstood what 'Message' meant, and so I ended up breaking things with my changes without the reason being obvious to me. I looked into the source code and I can see now that indeed 'Messages' refer to API calls and not direct messages, and that there is no 'Direct Message' rate limit.

If I let 'Messages' stay high I can adjust the other values to reasonable values and everything works fine.

Thanks a lot for your help!! I am surprised and happy it actually worked out and I understand a little more 😁