Semantic relationship between "немец" and "немой"?

Question

I believe I was taught (when I studied Russian decades ago) that немец is related to немой, and that the semantic connection is that if one were to speak to one of these German types, rather than responding, they would merely stare back mutely. But I wonder if that's a bit of folk etymology.

Wiktionary does trace both of them back to a shared origin in a reconstructed Proto-Slavic *němъ. So maybe my professor's story was right? Well, per its Wiktionary entry, that reconstructed word had two meanings. The second it gives is "dumb, mute (not able to speak)," but the first is "unclear or incomprehensible speaker, muttering, mammering." So maybe the prof's imagery was askew. Perhaps the idea was not that they didn't respond when addressed, but rather that when they did speak, no sensible person (i.e., Slavic speaker) could comprehend their meaning.

So what do we know about the semantic notions motivating the word немец?

Answer 1

Initially, the word "немец", derived from "немой", was used to denote all foreigners living in the West.

An example of the word from a document from 1588 (in modern spelling):

«С немцев английских, с испанских и других немцев брать судовую проездную пошлину приказано брать как с русских.»

"немец английский" - an Englishman. "Немецкая слобода" - a residential area for expats in Moscow in the 17th century. Since at some point a significant part of the inhabitants of this area were Germans, the meaning narrowed to Germans.