[werk_ag]

Definitely not supported in Raspberry as well:

"Problem USB to Serial Adapters
HL-340

CH340 Chipset - Currently not supported by RPi but there is a patch of kernel code here, but it is for a 2.X kernel. If you find you have bought one of these, then it may work under Windows, but as of writing there is no support for RPi. Otherwise you can have a go at getting the patch to work."

I can't agree. I have an RX test unit, built with an Arduino with the CH340 chipset running CumulusMX for weeks in a PI B+ without any major problem.

Question: If I am to replace the CH340 Nano with an FTDI Nano will it work without modification (I mean with a C3 instead of an R3)?

I tested it recently, and can confirm that the anti auto-reset circuit with the C3 capacitor, also work with Arduinos with the FTDI chipset.