I’ve been using Docker long enough to know my way around Compose files, containers, and the usual networking settings. But for years, I treated port configuration as one of those things that simply worked if the syntax was right. That changed when I started dealing with more complex setups and had to troubleshoot why services behaved differently depending on where a connection came from. I realized I had been looking at Docker networking too narrowly. The commands weren’t the hard part. The missing piece was understanding what Docker was doing between the application, container, host, and network. That shift completely changed how I configure containers.