Security of ssh and dlna

I recently read a post about the dangers of ruing ssh on a non-standard port, and why it's a bad idea, something I've done since I started using ssh. I have both my boxes ruing on ports above 4000 and both forwarded to through a virtual server on a nat router, both are also using 4096 bit, encrypted, rsa private key authentication only. Here's a link to the article: https://www.adayinthelifeof.nl/2012/...2-is-bad-idea/
The jist of this article is it's a bad idea to do this because ssh is started by root and opens a low port that only root is allowed to open, by using a higher random port it would be easy for a skilled cracker to write a script to fake ssh into giving the cracker root access (this stuff is a lot above my head), because of the high port number that any non root process is capable of opening. There is a disclaimer before the article that some of the writers points are no longer valid. His basic premise remains though. One premise is that the reason we move away from 22 is to deny those searching for the well known port to limit probing attacks. His claim is these attacks should be of no conce if other proper security precautions are taken, mainly elimination of password login in favor of private key authentication. Is this true? And is there any real danger in using higher non-standard ports?

With regards to dlna, I recently set up minidlna on an old laptop for my movie collection, it's set up to not be accessible outside my local network (I think) what are the dangers posed by this service and are there and good ways to secure it to limit those risks? I'm new to ruing any type of server so I'm sure any ideas will be helpful.