Flex 6400 M not linked to computer what is the best Update 3 1 12 or 3 1 8 ?

FIRST upgrade the front of the radio, when you first turn it on it should have a list of different versions of software on the screen CLICK on 3.1.12, let it do it's thing.

Then on your computer be sure to download and install 3.1.12 and then you should be done.

if you don't see the Multi-versions on the Main Radio screen when you first turn on the radio then you will have to do a couple key clicks on the radio screen to log it off (NOT the power button) so the version screen will come on.

BUT it is VERY important to update the M series Radio first then do SmartSDR.

if you don't see the version window on the radio front panel, From the Radio Click Menu, then about 1/3 of the way to the right on the grey screen you will see a "Switch Version" screen, Click it and you will be disconnected from the radio and it will put you at the version screen, Now click on the "3.1.12" and the radio will update the Control head and the Radio.

Hope this helps