The End of my Exposed Host Experiment
For months I have been hosting Immich, Photoprism and AudioBookShelf and the experiment has been a success. It has been stable and reliable so far and I did not detect anyone accessing my server without permission.
I had these services as Exposed Host via the Swisscom router DMZ setting. it was easy to setup and run with no issues for the duration of the experiment. I closed the DMZ because no one but me was accessing these services after five to six months but me. Keeping services exposed for, me, alone, to use them, is not necessary.