You read it wrong. its 2.1 Links to download the firmware are in the wiki for the firmware, the dropbox link is mine btw
Also many of the firmware version numbers were wrong when you read it, someone incorrectly decided to add many incorrect firmware versions. I undid those.
wiki.radioreference.com
You can use the latest and last 2.1, 1.4 firmwares to go all the way, no need to do any of the intermediary firmwares.