If you experience request time outs with your application, there are several things that could be happening.
Old Puma Versions
If you're running an old version of Puma, try upgrading to the latest version. Older Puma versions don't always hot reload properly and this has been fixed in newer versions. For example, we've seen this happen with Puma 4.3 several times.
Update the version in your Gemfile, bundle install, commit changes, and re-deploy your application.
If you've modified firewall rules on your servers or hosting provider, check to make sure you're not blocking the request in your firewall configuration.