I reached the limit in the post body so I can continuing it here

[I am no longer able to post pictures , imagine here the text, it is no longer garbled]

So the “real” serial port worked, but not my adapters !

So my question is this

What doesn’t the serial output work with these adapters ?

I imagine it is because the TTL voltage levels versus the serial voltages levels.

How do I do level shiting, preferably passively so that my adapters work ?

Especially my serial to ethernet adapter, which I don’t know any economical alternatives for.

These are WCH CH9121 by the way !