ZeroMQ Subscriber in Rails Worker Fails to Receive Messages, but Works with QLStats

I am trying to subscribe to the ZeroMQ from my Quake Live server. I registered the server on QLStats (green status here: https://qlstats.net/panel2/servers.html), confirming that the PUB socket is functioning correctly. Below I pasted log entries where I can see the QLStats server authenticating correctly. However, my Rails worker using ffi-rzmq fails to receive any messages (I am running this locally on a brand new project).

Here is the Rails worker code:

require 'ffi-rzmq'require 'json'class ZmqSubscriberJob  include Sidekiq::Job  def perform    context = ZMQ::Context.new    subscriber = context.socket(ZMQ::SUB)    username = ENV['ZMQ_USERNAME']&.b    password = ENV['ZMQ_PASSWORD']&.b    subscriber.setsockopt(ZMQ::PLAIN_USERNAME, username)    subscriber.setsockopt(ZMQ::PLAIN_PASSWORD, password)    zmq_url = "tcp://#{ENV['ZMQ_HOST']}:#{ENV['ZMQ_PORT']}"    subscriber.connect(zmq_url)    subscriber.setsockopt(ZMQ::SUBSCRIBE, '')    Rails.logger.info "Connected to ZeroMQ PUB socket at: #{zmq_url}, listening for all events."    loop do      message = ''      subscriber.recv_string(message)      Rails.logger.info "Received message: #{message}"    rescue => e      Rails.logger.error "Error: #{e.message}"    end  ensure    subscriber&.close    context&.terminate  endend

What I Have Verified:

1. The Quake Live server logs confirm the PUB socket is running:

zmq PUB socket: tcp://0.0.0.0:27960

2. I can also see that the QLStats server is logging in correctly:

I: 25-01-02 10:39:09 zauth: ZAP request mechanism=PLAIN ipaddress=23.88.103.193I: 25-01-02 10:39:09 zauth: - allowed (PLAIN) username=XXX password=XXXI: 25-01-02 10:39:09 zauth: - ZAP reply status_code=200 status_text=OK

3. ZMQ_USERNAME and ZMQ_PASSWORD match the credentials configured in the server and shown in the logs.
4. No error is logged by the Rails worker, but it does not receive any messages.

Environment Details

• Rails 7.2.2.1
• ffi-rzmq gem version 2.0.7

I looked at this to get a grasp about how it works: https://github.com/MinoMino/minqlx/blob/master/python/minqlx/_zmq.py

I tried to create a Python version just in case, but that didn't work either. I also created one in plain rails (no workers), no luck.

I believe it's something really simple that I am missing.

Could it be a problem with the version of ffi-rzmq?Any pointers on how to solve this?