I will now answer my own question. I have contacted Kingston and sent them the excerpt from my recently purchased Synology DS3622xs+. The Synology 2x8GB Ram installed in my DS3622xs+ is NOT compatible with the Kingston Ram KSM26SED8/16HD anymore. "Therefore, effective immediately, we will discontinue support for the DiskStation DS3622xs+. We will be reviewing support for other Synology systems shortly to see if we need to make the same decision for the remaining models in this range."

I have the bar in a DS1821. A warning appears in the log after every restart (not certified), but it runs perfectly.

So my NAS works perfectly with them.
I even have two of them in it.