The trouble with remote access is that it involves more than the components you do or don’t update in your own environment. It particularly involves components outside your immediate control, such as the technical configuration of how your ISP connects your router to their network and the internet.
I wrote this guide some time ago to help pinning down what might be causing the remote access issues in a specific setup. I’m not aware of any specific remote access issues with the Plex Media Server in general.