one of the things I often hear is that people don't like to go repeat the same action a bunch of times, so for example if one has a bunch of microservices meant to be run through docker one does not want to go set ports up for all scenarios etc. and to have every member of a team do the same thing, and maybe updating documentation because you've written in port 5000 all over the place, hah hah, but no to answer your no doubt sincere question looking up open ports does not take a while.

What takes a while is another engineering principle that people are sometimes bitten by, trying to understand why a change in the system has occurred - in this case why your port that you always use is suddenly no longer open despite you not having done anything that you are aware of that might have closed it. Of course you want to understand why this change has happened because it seems weird, is there something nefarious going on at port 5000 now!?! Also because of all the things said above about wanting to not change all occurrences of 5000 in your developer docs and so forth so it would be nice if you figure out, as was shown as the top voted answer of the article, that you could go to somewhere in settings and turn off this usage of the port. I mean you could just scan and change what port you use to another currently open port without worrying about any of this stuff, which I guess would have worked in this case but I can't help but feel that would not really appear the best move whenever strange unexplained port usage changes occur. Your mileage evidently varies.