When people who have non-English last names tell others incorrectly how to say their name

Highly niche gripe here. Look, I don't expect perfect pronunciation with a perfect accent, but you should at least know enough about your own heritage to get those pretty much close enough correct.

Using Vietnamese as an example. Most Vietnamese people tend to have the name Nguyen, which is very confusing for non-Viets who don't know the language. So, they're going to ask a Vietnamese person how to say it. The problem is, there are a lot of Viets who haven't been exposed to the language enough to know how it's pronounced, or how to teach someone how to say it. So, they teach them wrong.

I see all kinds of pronunciations: wen, win, new-yen. Come on, those first 2 are blatantly wrong, given how they clearly leave out the "n" at the beginning. Let me just say it now, the closest you can get as a non-Viet speaker is "nwen", that's good enough. Maybe "ngweng" if you want to be extra. That's before we add tone with diacritics, but those aren't necessary for everyone to understand what you're saying. The phonemes and digraphs in "Nguyen" are present in English as well, so even if you don't speak Viet, if you have the name, you're obligated to get it right.