I have known @stephdl for many years, since the SME Server days, where I first came to appreciate his technical contributions and his constant willingness to help anyone who needed it. When I found him again in the NethServer community, his role in my experience went well beyond that of a great module developer he was, in every sense, a mentor.
The moments where I turned to his guidance have been many… so many that I probably don’t remember them all. But some milestones stay with me as important steps in my own journey: setting up the mirror for NethServer 6 and 7, my first hesitant pull requests, and above all learning how to contribute meaningfully to QA during the migration from NethServer 6 to 7.
One moment I have never forgotten goes back to the mirror itself: when I created it, building heavily on the work he had done before — something he had encouraged me to do — his comment was simply: “Knowledge is meant to be shared.” Few words, but important ones, and above all always backed by action: available, patient, able to explain things without ever making you feel inadequate.
It was thanks to him that I found the courage to move from being a simple user to someone who tries to give something back to the project.
From those first contributions around the NS6 mirror (Help in testing mirror/repo - #6 by stephdl) and module testing (Nethserver-arpwatch: Needs Tests - #4 by stephdl), many other pieces of advice, answers and bugfixes followed over the years. And still today his posts, his documentation and his GitHub account 
are a reference I go back to whenever I need it: 11 years later, for the NS8 repository, I did exactly the same thing (Create a ns8 repository for developers).
I am convinced that his path, built entirely in the field, driven by curiosity, by the desire to keep learning and contributing, and by generosity toward others, fully deserves recognition. It is undeniable that many of us have used and continue to use his work across SME, NS6-7-8 and NethSecurity, and above all have benefited from his support and guidance over the years.
I will not list his technical growth as a developer and sysadmin, others have already covered that well, and frankly, a quick look at his GitHub says it all.
Good luck Steph, and thanks for everything!